Toner for developing electrostatic image, two-component developer and image forming apparatus

ABSTRACT

A toner for developing an electrostatic image, including: toner base particles each including a binder resin and a releasing agent; and inorganic fine particles, wherein the toner includes the inorganic fine particles as an external additive on a surface of the toner base particle, wherein the toner base particles have a BET specific surface area of 2.5 m 2 /g to 5.0 m 2 /g, and wherein the inorganic fine particles comprise inorganic fine particles (A) which are each a secondary particle where a plurality of primary particles are coalesced together.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to: a toner used as a developer when anelectrostatic image formed by electrophotography, electrostaticrecording and so on is developed; a two-component developer includingthe toner; and an image forming apparatus using the toner.

2. Description of the Related Art

After a charging step which uniformly charges an image-forming region ona surface of an image bearing member, an exposing step which writes onthe image bearing member, a developing step which forms an image on theimage bearing member by a frictionally charged toner and a transfer stepwhich transfers the image on the image bearing member directly on aprinting sheet or indirectly via an intermediate transfer member, animage forming apparatus fixes the image on the printing sheet. Also, atransfer residual toner not transferred on the image bearing member, isscraped from the image bearing member by a cleaning step, and a nextimage forming process is carried out.

As the developer to be used, there are a two-component developercomposed of a toner and a carrier and a one-component developer composedonly of a magnetic or a non-magnetic toner. In general, these toners aremanufactured by a melt-kneading pulverization method, where a resin, apigment, a charge controlling agent and a releasing agent aremelt-kneaded, followed by cooling, pulverization and classification, buta particle diameter and a shape of the toner are not uniform, and it isdifficult to control them.

Under such circumstances, there is an attempt to intentionally control aparticle diameter of toner particles in recent years, trying to solvethe aforementioned problems, and toner polymerization methods such asemulsion-polymerization method and dissolution-suspension method becamepopular as aqueous granulation.

In recent years, due to increased demand for higher quality, especiallyto achieve a high-definition image in color image formation, there is agrowing demand for reduction and homogenization of the toner particlediameter. When an image is formed using a toner having a wideparticle-diameter distribution, problems of contamination of adeveloping roller, a charging roller, a charging blade, aphotoconductor, a carrier and so on by fine-powder toner and tonerscattering become severe, and it is difficult to fulfill high qualityhigh reliability at the same time. On the other hand, when the particlediameter is uniform and the particle diameter distribution is sharp,developing behavior of individual toner particles becomes uniform, andfine-dot reproducibility significantly improves.

In general, as a fixing system in the electrophotography, a heat-rollerheating system that a heat roller is directly pressed on a toner imageon a recording medium for fixing is widely used in terms of energyefficiency. The heat-roller heating system requires a large amount ofelectric power for fixing. Thus, in view of saving energy, reduction ofenergy consumption of the heat roller has been studied. For example, asystem that an output of a heater for a heat roller is reduced when animage is not being output and that a temperature of the heat roller isincreased by increasing the output of the heater when an image is beingoutput is generally used.

However, in this case, in order to increase the temperature of the heatroller from a sleep mode to a temperature required for fixing, a standbytime of around several tens of seconds is required, and this standbytime is stressful for users. Also, when an image is not output, it isdesired to suppress energy consumption by completely turning off theheater. To respond to these requests, it is necessary to reduce a fixingtemperature of a toner itself and to reduce the fixing temperature ofthe toner available for fixing.

With the development of electrophotographic technologies, a toner usedin the developer is required to have superior low-temperature fixingproperty, storage stability (blocking resistance) and stress resistance,there have been various attempts to use a polyester resin having highcompatibility with a recording medium and so on and superiorlow-temperature fixing property compared to a styrene resin which hasbeen generally and conventionally used as a binder resin for a toner.

However, a toner designed with an emphasis on low-temperature fixingproperty has a trade-off relationship with storage stability and stressresistance by softening the resin, and it is required to achieve theboth.

In order to solve this problem, a toner having a capsule structurecomposed of core particles including a resin having a low glasstransition temperature, and an outer shell which is formed to coat asurface of the core particles and includes a resin having a high glasstransition temperature has been proposed.

For example, a capsule toner is proposed, wherein a mixed solution of acore-material constitutional material including a monomer (polymerizablemonomer) as a raw material of a thermoplastic resin and an outer-shellconstitutional material including non-crystalline polyester is dispersedin a dispersion medium, and by an in-situ polymerization method, inparallel with a formation of core particles by polymerization, an outershell is formed by distributing unevenly the outer shell constitutionalmaterial on a surface of liquid droplets (see Japanese Patent (JP-B) No.3030741).

Also, a toner is proposed, wherein an aqueous dispersion liquid of resinparticles obtained by emulsion polymerization or soap-free emulsionpolymerization is added to polymer particles (core particles) obtainedby suspension polymerization so that 95% or more of a surface of thepolymer particles is covered by the fine particles, and then it isheated to a temperature of a glass transition temperature of the polymerparticles or higher so that the surface has substantially no asperity(see Japanese Patent Application Laid-Open (JP-A) No. 2000-112174).

Also, a toner is proposed, wherein resin particles having at least twodifferent glass transition temperatures and a toner core material (coreparticles) are mixed, and a coating resin is disposed on the toner corematerial by fixing or fusing the resin particles while increasing thetemperature (see JP-A No. 2001-201891).

Further, a toner obtained by a process including a first step and asecond step is proposed, wherein a surface of a core toner (coreparticles) composed of a binder resin having an average particlediameter of 2 μm to 20 μm and a glass transition temperature of 30° C.to 55° C. is coated with resin particles encapsulating a wax followed byfixing or fusing in the first step and is coated with resin particleswhich does not include a wax followed by fixing or fusing in the secondstep (see JP-A No. 2001-235894).

However, in the patent literatures described above, it is possible toimprove the problems of storage stability, blocking resistance andaggregation property under a high temperature, but measures for stressesin the developing step have not been taken, degradation of the toner dueto developing stresses, and degradation of transfer properly, developingproperty and cleanability attributed thereto are concerned.

In order to improve transfer property, developing property andcleanability, it is disclosed to combine inorganic fine particles havinga medium particle diameter with an average particle diameter of 20 μm to40 μm as an external additive (see JP-A No. 03-100661).

Also, it is disclosed to use inorganic fine particles having a largeparticle diameter in order to suppress embedding of an external additivedue to stresses in a developing machine (see JP-B No. 3328013, JP-A No.09-319134, JP-B No. 3056122).

With these, favorable cleanability, transfer property and developingproperty may be obtained initially, but adhesive strength of theinorganic fine particles vary from particles to particles, and theinorganic fine particles liberate over time, causing contamination inthe developing machine or around a photoconductor or resulting ininsufficient transfer property and cleanability.

On the other hand, as a means to reduce non-electrostatic adhesionbetween toner particles and an electrophotographic photoconductor orbetween toner particles and an intermediate transfer member, a method toadjust a type or an amount of an external additive (especially, addingan external additive having a large particle diameter) is proposed (seeJP-A No. 08-176310). With this method, it is possible for the tonerparticles to improve transfer efficiency with an effect of reducednon-electrostatic adhesion, and at the same time, it is possible toobtain effects such as improved development stability and cleaning.

Further, with reduction of particle diameter of a toner and control of ashape of toner particles in recent years, an added amount of an externaladditive increases, there are problems of filming, carrier contaminationand so on. Also, with toner particles having a shape of a complexstructure, it is initially possible to produce a high-quality image, butit becomes difficult to maintain the high-quality image over time due tothe external additive embedded or the external additive rolling intoconcave portions. Especially, in a case where a fine irregular structureon a surface of the toner becomes large, loss of functions increases dueto the embedding or rolling of the external additive. Also, when anexternal additive having a large particle diameter is added, supplyproperty of the toner is affected due to small improvement effect oftoner fluidity.

The toner particles described above can initially improve transferefficiency of an image forming apparatus. However, the toner receivesmechanical stresses such as stirring over a long period of time in adeveloping apparatus of the image forming apparatus, causing theexternal additive embedded in the toner base or rolling into concaveportions of a surface of the toner base. As a result, an effect ofreduced adhesion by the external additive is not exhibited, and transferefficiency of the image forming apparatus decreases. Especially, in acase of a high-speed machine, this mechanical stresses is large due tovigorous stirring in a developing apparatus, and it is likely thatembedding of the external additive in the toner base is accelerated.Thus, it is expected that transfer efficiency is reduced at a relativelyearly stage. In recent years, it is disclosed to suppress embedding byusing an external additive having a relatively large particle diameter,but there are problems that an effect of imparting toner fluidity is lowas described above and that the free external additive causes filming.

Thus, in order to maintain high transfer efficiency in a high-speedmachine in a stable manner over a long period of time, it is necessaryto control surface property (mechanical strength) of a toner so that anexternal additive exists on the surface without being embedded into atoner base despite receiving mechanical stresses. Further, when thesurface property (mechanical strength) of the toner is excessivelystrengthened (hardened), attention should be paid to side effects ofdegraded fixability, e.g. inhibition of toner melting during fixing orinsufficient bleeding of a releasing agent on a fixing roller duringfixing in a case of a toner including a releasing agent such as wax andso on. Further, it is possible to maintain high transfer rate by asimple spheronization process of a toner, but it causes a side effect ofreduced cleanability of the toner.

Also, for the purpose of improving low-temperature fixing property, amethod of introducing crystalline polyester to a polymerization methodis disclosed. As a method for preparing a dispersion liquid ofcrystalline polyester, a method for preparing a dispersion liquid usinga solvent for phase separation is disclosed (see JP-B No. 3328013). Byusing crystalline polyester, it is possible to achieve low-temperaturefixing property. However, this is insufficient because an externaladditive is likely to be embedded with the toner including crystallinepolyester, resulting in decrease in transfer efficiency.

Also, use of a non-spherical external additive for improving imagedensity stability is disclosed (see JP-B No. 3684074, JP-A No.2010-224502). It is possible to achieve improved transfer efficiency bythe non-spherical external additive. However, an amount of adhesion of atoner decreases when an aggregate of non-spherical particles arepresent. Aggressiveness toward a photoconductor increases due to theaggregate of free non-spherical particles, and it causes scratches onthe photoconductor. However, such a problem of is not mentioned.

In other words, a spherical toner having a small particle diameter hasbeen developed by aqueous granulation in recent years, but there remainsa challenge to cleanability. Surface irregularities increases with tonerbase particles having a high BET specific surface area, and it isadvantageous in cleanability. Also, it reduces an effective coverage ofan external additive, and it is effective for low-temperature fixingproperty. However, for a toner having a high specific surface arearelative to toner base, there are many cases where an external additivecannot sufficiently exhibit its effect under stresses due to itsirregularities because of the external additive rolling into concaveportions or the external additive embedded in convex portions.

SUMMARY OF THE INVENTION

The present invention aims at solving the above problems in theconventional technologies and at achieving the following objection. Thatis, the present invention aims at providing a toner obtained from tonerbase particles having a high BET specific surface area, which canexhibit a sufficient effect of an external additive even under stresses,has superior cleanability, improves transfer efficiency, eliminatesimage defects at each transfer and provides an image having favorablereproducibility over time, and has low-temperature fixing property andhigh storage stability at a high temperature.

Means for solving the problems are as follows. That is,

A toner for developing an electrostatic image of the present inventionis a toner for developing an electrostatic image including:

toner base particles including at least a binder resin and a releasingagent; and

inorganic fine particles,

wherein the toner includes the inorganic fine particles as an externaladditive on a surface of the toner base particles,

wherein the toner base particles have a BET specific surface area of 2.5m²/g to 5.0 m²/g, and

wherein the inorganic fine particles include inorganic fine particles(A) which are each a secondary particle where a plurality of primaryparticles are coalesced together.

The present invention may solve the conventional problems and achievethe objectives above, and it is possible to provide a toner which hassuperior cleanability, improves transfer efficiency, eliminates imagedefects at each transfer and provides an image having favorablereproducibility over time, and has low-temperature fixing property andhigh storage stability at a high temperature.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic explanatory diagram illustrating one example of animage forming apparatus used in the present invention.

FIG. 2 is a schematic explanatory diagram illustrating another exampleof an image forming apparatus used in the present invention.

FIG. 3 is a schematic explanatory diagram illustrating another exampleof an image forming apparatus used in the present invention.

FIG. 4 is a schematic explanatory diagram illustrating a part of theimage forming apparatus of FIG. 3.

FIG. 5 is an FE-SEM image of inorganic particles (A) as an externaladditive of a toner of the present invention, with an arrow indicating asecondary particle diameter.

FIG. 6 is an FE-SEM image of inorganic particles (A) as an externaladditive of a toner of the present invention, with an arrow indicating aprimary particle diameter.

DETAILED DESCRIPTION OF THE INVENTION Toner for Developing anElectrostatic Image

A toner for developing an electrostatic image of the present invention(hereinafter, it may be simply referred to as a “toner”) is a toner fordeveloping an electrostatic image including: toner base particlesincluding at least a binder resin and a releasing agent; and inorganicfine particles, wherein the toner includes the inorganic fine particlesas an external additive on a surface of the toner base particle, thetoner base particles have a BET specific surface area of 2.5 m²/g to 5.0m²/g, and the inorganic fine particles include inorganic fine particles(A) which are each a secondary particle where a plurality of primaryparticles are coalesced together.

The toner of the present invention having the above features hassuppressed embedding or moving into concave portions of the externaladditive, which is expected to occur when stresses are applied on thetoner such as being stirred in a developing device; thus, it is possibleto maintain high transfer rate over time. Further, high cleanability isensured due to surface irregularities of the toner, and at the sametime, effective coverage of the external additive decreases;accordingly, it has a significant effect on low-temperature fixingproperty.

Usually, when a toner having a small particle diameter is used in anelectrophotographic image forming apparatus, non-electrostatic adhesionbetween toner particles and an electrophotographic photoconductor orbetween the toner particles and an intermediate transfer memberincreases, resulting in further decreased transfer efficiency.Especially, when a toner having a small particle diameter is used in ahigh-speed machine, it has been known that decrease of transferefficiency during secondary transfer is significant. This is becausetime for the toner particles subjected to a transfer electric field at anip portion during transfer, especially at a nip portion duringsecondary transfer is shortened because of increased processing speed aswell as increased non-electrostatic adhesion with an intermediatetransfer member due to reduced particle diameter of the toner.

However, it is possible to achieve sufficient transfer efficiency withthe toner of the present invention even when non-electrostatic adhesionof toner particles are reduced due to suppressed embedding of theexternal additive in the toner base and when transfer time is shortenedas in a high-speed machine. Also, even when mechanical stresses arelarge over time as in a high-speed machine, the external additive itselfis difficult to roll, and it is unlikely that the external additivefalls into the toner concave portions and that the functions of theexternal additive are lost. Thus, it is possible to maintain sufficienttransfer efficiency in the long term. Accordingly, it eliminates theneed to reduce the BET specific surface area of the toner base forpreventing rolling of the external additive and ensuring fluidity, andat the same time, the BET specific surface area may be increased. As aresult, it is possible to reduce the effective coverage of the externaladditive and to advantage low-temperature fixing property. Further,since an effect equivalent to increased degree of deformation isexpected, cleanability over a long period of time may be ensured.

<Production of Toner Base Particles>

The toner base particles include at least a binder resin and a releasingagent, and it further includes other components according to necessity.

According to the present invention, the BET specific surface area of thetoner base particles is not particularly restricted as long as it is 2.5m²/g to 5.0 m²/g, and it may be appropriately selected according topurpose. Nonetheless, it is preferably 3.0 m²/g to 4.0 m²/g. When thisis less than 2.5 m²/g, it is likely that the external additive isembedded in the base due to the low BET specific surface area. Sincehigh transfer property cannot be maintained or effective coverage of theexternal additive increases, there is a concern that low-temperaturefixing property is inhibited. On the other hand, when it exceeds 5.0m²/g, degree of deformation is too high, and effective coverage as theexternal additive is too low. Thus, an adverse effect on storagestability is concerned.

In the preferable toner manufacturing method described hereinafter, forexample, the BET specific surface area of the toner base particles maybe adjusted by a mixing time or an aging temperature after addition ofan aqueous medium in manufacturing the toner base particles. Forexample, coalescence (convergence) of emulsified particles proceeds byincreasing the mixing time after addition of the aqueous medium,resulting in decreased surface irregularities. Also, by increasing theaging temperature, a surface of the binder resin itself is tanned,resulting in the surface smoothed without irregularities.

[Method for Measuring Toner Properties] <Measurement of Bet SpecificSurface Area of Toner Base>

The BET specific surface area of the toner is measured using aMicromeritics Automatic Surface Area and Porosimetry Analyzer TRISTAR3000 (manufactured by Shimadzu Corporation).

Specifically, 1 g of the toner is placed in a dedicated cell, and thededicated cell is degassed using a dedicated degassing unit for TRISTAR,VACUPREP 061 (manufactured by Shimadzu Corporation).

The degassing is carried out at a mom temperature and under a reducedpressure of at least 100 mtorr or less for 20 hours.

The BET specific surface area in the dedicated cell after degassing maybe automatically measured by TRISTAR 3000.

Here, a nitrogen gas is used as an absorption gas.

<<Binder Resin>>

The binder resin is not particularly restricted, and it may beappropriately selected according to purpose. Heretofore known binderresins such as polyester resins, silicone resin, styrene-acrylic resins,styrene resins, acrylic resins, epoxy resins, diene resins, phenolicresins, terpene resins, coumarin resins, amide-imide resins, butyralresins, urethane resins, ethylene-vinyl acetate resins and so on may beused. These may be used alone or in combination of two or more, and itis preferable to include at least two types of resins.

Among these, the polyester resins are preferable as a resin phase forthe toner manufacturing method of the present invention since the resinshave sharp-melt property during fixing, smoothen a surface of an imageand have sufficient flexibility even when a molecular weight thereof isreduced. It is also possible to use other resins further combined withthe polyester resins.

The polyester resins used in the present invention are obtained bypolyesterification of one type or two or more types of a polyolrepresented by General Formula (1) below; and one type or two or moretypes of a polycarboxylic acid represented by General Formula (2) below.

A-(OH)m  (1)

[In the formula, A represents an alkyl group, an alkylene group, anaromatic group which may have one or more substituents or a heterocyclicaromatic group, having 1 to 20 carbon atoms; m represents an integer of2 to 4.]

B—(COOH)n  (2)

[In the formula, B represents an alkyl group, an alkylene group, anaromatic group which may have one or more substituents or a heterocyclicaromatic group, having 1 to 20 carbon atoms; n represents an integer of2 to 4.]

Specific examples of the polyol represented by General Formula (1)include ethylene glycol, diethylene glycol, triethylene glycol,1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, neopentylglycol, 1,4-butenediol, 1,5-pentanediol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, dipropylene glycol, polyethylene glycol, polypropyleneglycol, polytetramethylene glycol, sorbitol, 1,2,3,6-hexane tetrol,1,4-sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol,1,2,4-butanetriol, 1,2,5-pentanetriol, glycerol, 2-methylpropanetriol,2-methyl-1,2,4-butanetriol, trimethylolethane, trimethylolpropane,1,3,5-trihydroxymethylbenzene, bisphenol A, bisphenol A ethylene oxideadduct, bisphenol A propylene oxide adduct, hydrogenated bisphenol A,hydrogenated bisphenol A ethylene oxide adduct, hydrogenated bisphenol Apropylene oxide adduct and so on.

Specific examples of polycarboxylic acid represented by General Formula(2) include maleic acid, fumaric acid, citraconic acid, itaconic acid,glutaconic acid, phthalic acid, isophthalic acid, terephthalic acid,succinic acid, adipic acid, sebacic acid, azelaic acid, malonic acid,n-dodecenylsuccinic acid, isooctylsuccinic acid, isododecenylsuccinicacid, n-dodecylsuccinic acid, isododecylsuccinic acid, n-octenylsuccinicacid, n-octylsuccinic acid, isooctenylsuccinic acid, isooctylsuccinicacid, 1,2,4-benzenetricarboxylic acid, 2,5,7-naphthalenetricarboxylicacid, 1,2,4-naphthalenetricarboxylic acid, 1,2,4-butanetricarboxylicacid, 1,2,5-hexanetricarboxylic acid,1,3-dicarboxyl-2-methyl-2-methylenecarboxypropane, 1,2,4-cyclohexanetricarboxylic acid, tetra(methylenecarboxyl)methane,1,2,7,8-octanetetracarboxylic acid, pyromellitic acid, EMPOL trimeracids, cyclohexane dicarboxylic acid, cyclohexanedicarboxylic acid,butanetetracarboxylic acid, diphenylsulfonetetracarboxylic acid,ethylene glycol bis(trimellitic acid) and so on.

—Crystalline Polyester Resin—

As the polyester resin, a crystalline polyester resin may be included.

Favorable examples of the crystalline polyester resin includecrystalline polyester synthesized using: as an alcohol component, asaturated aliphatic diol compound having 2 to 12 carbon atoms,especially 1,4-butanediol, 1,6-hexanediol, 1,8-octanediol,1,10-decanediol, 1,12-dodecanediol and derivatives thereof, and at leastas an acid component, dicarboxylic acid having 2 to 12 carbon atomsincluding a double bond (C═C bond) or a saturated dicarboxylic acidhaving 2 to 12 carbon atoms, especially fumaric acid, 1,4-butanedioicacid, 1,6-hexanedioic acid, 1,8-octanedioic acid, 1,10-decanedioic acid,1,12dodecanedioic acid and derivatives thereof.

Among these, it is preferably configured only of one type of the alcoholcomponent selected from 1,4-butanediol, 1,6-hexanediol, 1,8-octanediol,1,10-decanediol, and 1,12-dodecanediol and one type of a dicarboxylicacid component selected from fumaric acid, 1,4-butanedioic acid,1,6-hexanedioic acid, 1,8-octanedioic acid, 1,10-decanedioic acid and1,12-dodecanedioic acid in view of further reducing a temperaturedifference between an endothermic peak temperature and an endothermicshoulder temperature.

Also, as a method to control crystallinity and softening point of thecrystalline polyester resin, for example, non-linear polyester obtainedby condensation polymerization with additions of polyhydric alcoholhaving 3 or more valences such as glycerin and so on to the alcoholcomponent and polycarboxylic acid having 3 or more valences such astrimellitic anhydride as the acid component in synthesizing thepolyester is designed and used.

A molecular structure of the crystalline polyester resin of the presentinvention may be confirmed by solution and solid-state NMR measurementsand in addition by x-ray diffraction, GC/MS, LC/MS and IR measurements.Conveniently, it is confirmed, for example, as an absorption based onSCH (out-of-plane bending vibration) of olefins at 965±10 cm⁻¹ or 990±10cm⁻¹ in an infrared absorption spectrum.

—Non-Crystalline Polyester Resin—

In the present invention, a non-crystalline, non-modified polyesterresin may be used as the binder resin component. It is preferable that amodified polyester resin obtained by crosslinking and/or elongationreaction of a binder resin precursor composed of a modified polyesterresin and the non-modified polyester resin are at least partiallydissolved. Thereby, it is possible to improve low-temperature fixingproperty and hot-offset resistance. Accordingly, the polyols and thepolycarboxylic acids of the modified polyester resin and thenon-modified polyester resin preferably have similar compositions. Also,as the non-modified polyester resin, it is possible to use thenon-crystalline polyester resin used for the crystalline polyesterdispersion liquid if it is non-modified.

An acid value of the non-modified polyester resin is usually 1 KOHmg/gto 50 KOHmg/g, and preferably 5 KOHmg/g to 30 KOHmg/g. Thereby, sincethe acid value is 1 KOHmg/g or greater, the toner is likely to havenegative-charging property. Further, affinity between paper and thetoner improves during fixing to the paper, and low-temperature fixingproperty may improve. However, when the acid value exceeds 50 KOHmg/g,charge stability, charge stability against environmental variations inparticular, may decrease. In the present invention, the non-modifiedpolyester resin has an acid value of preferably 1 KOHmg/g to 50 KOHmg/g.

The non-modified polyester resin has a hydroxyl value of preferably 5KOHmg/g or greater. The hydroxyl value is measured using a method basedon JIS K0070-1966.

Specifically, first, 0.5 g of a sample is accurately weighed in a 100-mLmeasuring flask, to which 5 mL of an acetylation reagent is added. Next,after it was heated in a warm bath at 100±5° C. for 1 hour to 2 hours,the flask is taken out from the warm bath and allowed to cool. Further,the flask is shaken with an addition of water to decompose aceticanhydride. Next, for complete decomposition of acetic anhydride, theflask is again heated in a warm bath for 10 minutes or greater and thenallowed to cool, and thereafter, a wall of the flask is thoroughlywashed with an organic solvent.

Further, using an automatic potentiometric titrator DL-53 TITRATOR(manufactured by Mettler-Toledo International Inc.) and an electrode,DG113-SC (manufactured by Mettler-Toledo International Inc.), thehydroxyl value is measured at 23° C., and it is analyzed using ananalysis software LabX Light Version 1.00.000. Here, a mixed solvent of120 mL of toluene and 30 mL of ethanol is used for calibration of theapparatus.

Here, measurement conditions are as follows.

Stir Speed [%] 25 Time [s] 15 EQP titration Titrant/Sensor TitrantCH3ONa Concentration [mol/L] 0.1 Sensor DG115 Unit of measurement mVPredispensing to volume Volume [mL] 1.0 Wait time [s] 0 Titrant additionDynamic dE(set) [mV] 8.0 dV(min) [mL] 0.03 dV(max) [mL] 0.5 Measure modeEquilibrium controlled dE [mV] 0.5 dt [s] 1.0 t(min) [s] 2.0 t(max) [s]20.0 Recognition Threshold 100.0 Steepest jump only No Range No TendencyNone Termination at maximum volume [mL] 10.0 at potential No at slope Noafter number EQPs Yes n = 1 comb. termination conditions No EvaluationProcedure Standard Potential1 No Potential2 No Stop for reevaluation No

—Modified Polyester Resin—

Examples of the modified polyester resin obtained by crosslinking and/orelongation reaction of a binder resin precursor composed of a modifiedpolyester resin include a urea-modified polyester resin, aurethane-modified polyester resin and so on.

Here, the urea-modified polyester resin may be used in combination with,other than a non-modified polyester resin, a polyester resin modifiedwith a chemical bond other than a urea bond such as polyester resinmodified with a urethane bond.

When the toner composition includes a modified polyester resin such asurea-modified polyester resin and so on, the modified polyester resinmay be manufactured by a one-shot method and so on.

As one example, a method for producing a urea-modified polyester resinis explained.

First, a polyol and a polycarboxylic acid are heated to 150° C. to 280°C. in the presence of a catalyst such as tetrabutoxy titanate,dibutyltin oxide and so on, and by removing generated water under areduced pressure according to necessity, a polyester resin having ahydroxyl group is obtained. Next, the polyester resin having a hydroxylgroup and a polyisocyanate are reacted at 40° C. to 140° C., and apolyester prepolymer having an isocyanate group is obtained. Further,the polyester prepolymer having an isocyanate group and amines arereacted at 0° C. to 140° C., and the urea-modified polyester resin isobtained.

The urea-modified polyester resin has a number-average molecular weightof usually 1,000 to 10,000, and preferably 1,500 to 6,000.

Here, a solvent may be used according to necessity in a case where apolyester resin containing a hydroxyl group and a polyisocyanate arereacted and a case where polyester prepolymer having an isocyanate groupand amines are reacted.

Examples of the solvent include those inert to an isocyanate group suchas aromatic solvents (toluene, xylene and so on); ketones (acetone,methyl ethyl ketone, methyl isobutyl ketone and so on); esters (ethylacetate and so on); amides (dimethylformamide, dimethylacetamide and soon); ethers (tetrahydrofuran and so on) and so on.

Here, when a non-modified polyester resin is used in combination, theresin manufactured in the same manner as the polyester resin having ahydroxyl group may be mixed in the solution after the reaction of theurea-modified polyester resin.

In the present invention, a crystalline the polyester resin, anon-crystalline polyester resin, a binder resin precursor and anon-modified resin may be used in combination as a binder resincomponent included in an oil phase, and binder resin components otherthan these resins may further be included. It is preferable to include apolyester resin as the binder resin component, and it is furtherpreferable to include the polyester resin by 50% by mass or greater.When a content of the polyester resin is less than 50% by mass,low-temperature fixing property may degrade. It is particularlypreferable that all the binder resin components are polyester resins.

Here, examples of the binder resin components other than the polyesterresin include: polymers of styrene or substituted styrene such aspolystyrene, poly(p-chlorostyrene), polyvinyltoluene and so on; styrenecopolymers such as styrene-p-chlorostyrene copolymer, styrene-propylenecopolymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalenecopolymer, styrene-methyl acrylate copolymer, styrene-ethyl acrylatecopolymer, styrene-butyl acrylate copolymer, styrene-octyl acrylatecopolymer, styrene-methyl methacrylate copolymer, styrene-ethylmethacrylate copolymer, styrene-butyl methacrylate copolymer, copolymerof styrene-methyl α-chloromethacrylate, styrene-acrylonitrile copolymer,styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer,styrene-isoprene copolymer, styrene-acrylonitrile-indene copolymer,styrene-maleic acid copolymer, styrene-maleic acid ester copolymer andso on; polymethyl methacrylate, polybutyl methacrylate, polyvinylchloride, polyvinyl acetate, polyethylene, polypropylene, an epoxyresin, an epoxy polyol resin, a polyurethane resin, a polyamide resin, apolyvinyl butyral, a polyacrylic acid, rosin, modified rosin, a terpeneresin, an aliphatic or alicyclic hydrocarbon resin, an aromaticpetroleum resin, chlorinated paraffin, paraffin wax and so on.

—Binder Resin Precursor Having a Site Capable of Reacting with aCompound Having an Active Hydrogen Group—

A binder resin precursor having a site capable of reacting with thecompound having an active hydrogen group (hereinafter “prepolymer”) isnot particularly restricted as long as it includes at least a sitecapable of reacting with a compound having an active hydrogen group, andit may be appropriately selected from heretofore known resins. Forexample, a polyol resin, a polyacrylic resin, a polyester resin, anepoxy resin, resins of derivatives thereof and so on may be used. Amongthese, the polyester resin is particularly preferable in view of highfluidity and transparency when melted. Here, these may be used alone orin combination of two or more.

The site capable of reacting with the compound having an active hydrogengroup in the prepolymer is not particularly restricted, and it may beappropriately selected from heretofore known substituents and so on.Examples thereof include an isocyanate group, an epoxy group, acarboxylic acid, an acid chloride group and so on. These may be usedalone or in combination of two or more. Among these, the isocyanategroup is particularly preferable. Among the prepolymers, a polyesterresin having a urea bond-forming group (RMPE) is particularly preferablein view of easy control of a molecular weight of a polymeric component,oil-less low-temperature fixing property of a dry toner, and inparticular, favorable releasing property and fixability ensured withouta releasing oil-coating mechanism against a heating medium for fixing.

Examples of the urea bond-forming group include an isocyanate group andso on. When the urea bond-forming group is the isocyanate group in thepolyester resin having a urea bond-forming group (RMPE), an isocyanategroup-containing polyester prepolymer (A) is particularly favorable asthe polyester resin (RMPE). The isocyanate group-containing polyesterprepolymer (A) is not particularly restricted, and it may beappropriately selected according to purpose. Examples thereof includethose obtained by a reaction of a polycondensate of a polyol (PO) and apolycarboxylic acid, which is obtained by a reaction of a polyesterresin having an active hydrogen group with a polyisocyanate (PIC) and soon. The polyol (PO) is not particularly restricted, and it may beappropriately selected according to purpose. Examples thereof include adiol (DIO), a polyol having 3 or more valences (TO), a mixture of thediol (DIO) and the polyol having 3 or more valences (TO) and so on.These may be used alone or in combination of two or more. Among these,the diol (DIO) alone, and the mixture of the diol (DIO) and a smallamount of the polyol having 3 or more valences (TO) are favorable.Examples of the diol (DIO) include alkylene glycols, alkylene etherglycols, alicyclic diols, alkylene oxide adducts of alicyclic diol,bisphenols, alkylene oxide adducts of bisphenol and so on.

As the alkylene glycols, those having 2 to 12 carbon atoms arepreferable, and examples thereof include ethylene glycol, 1,2-propyleneglycol, 1,3-propylene glycol, 1,4-butanediol, 1,6-hexanediol and so on.

Examples of the alkylene ether glycols include diethylene glycol,triethylene glycol, dipropylene glycol, polyethylene glycol,polypropylene glycol, polytetramethylene ether glycol and so on.

Also, examples of the alicyclic diols include 1,4-cyclohexanedimethanol, hydrogenated bisphenol A and so on. Also, examples of thealkylene oxide adducts of alicyclic diol include adducts of alkyleneoxide ethylene oxide, propylene oxide, butylene oxide and so on to analicyclic diol.

Also, examples of the bisphenols include bisphenol A, bisphenol F,bisphenol S and so on.

Also, examples of the alkylene oxide adducts of bisphenol includeadducts of alkylene oxide such as ethylene oxide, propylene oxide,butylene oxide and so on to bisphenols.

Among these, the alkylene glycol having 2 to 12 carbon atoms, alkyleneoxide adducts of bisphenol and so on are preferable, and the alkyleneoxide adducts of bisphenol and a mixture of the alkylene oxide adduct ofbisphenol and the alkylene glycol having 2 to 12 carbon atoms areparticularly preferable.

As the polyol having 3 or more valences (TO), those having 3 to 8valences or greater are preferable, and examples thereof includepolyhydric aliphatic alcohols having 3 or more valences, polyphenolshaving 3 or more valences, alkylene oxide adducts of polyphenols having3 or more valences and so on.

Also, examples of the polyhydric aliphatic alcohols having 3 or morevalences include glycerin, trimethylolethane, trimethylolpropane,pentaerythritol, sorbitol and so on. Also, examples of the polyphenolshaving 3 or more valences include trisphenols (e.g. TRISPHENOL PA,manufactured by Honshu Chemical Industry Co., Ltd.), phenol novolak,cresol novolak and so on. Also, examples of the alkylene oxide adduct ofpolyphenols having 3 or more valences include adducts of alkylene oxidesuch as ethylene oxide, propylene oxide, butylene oxide and so on to thepolyphenols having 3 or more valences.

A mixing mass ratio (DIO:TO) of the diol (DIO) and the polyol having 3or more valences (TO) in the mixture of the diol (DIO) and the polyolhaving 3 or more valences (TO) is preferably 100:0.01 to 10, and morepreferably 100:0.01 to 1.

The polycarboxylic acid (PC) is not particularly restricted, and it maybe appropriately selected according to purpose. Nonetheless, examplesthereof include a dicarboxylic acid (DIC), a polycarboxylic acid having3 or more valences (TC), a mixture of the dicarboxylic acid (DIC) andthe polycarboxylic acid having 3 or more valences and so on. These maybe used alone or in combination of two or more. Among these, thedicarboxylic acid (DIC) alone, or a mixture of the dicarboxylic acid(DIC) and a small amount of the polycarboxylic acid having 3 or morevalences (TC) is preferable.

Examples of the dicarboxylic acid (DIC) include alkylenedicarboxylicacids, alkenylene dicarboxylic acids, aromatic dicarboxylic acids and soon. Also, examples of the alkylenedicarboxylic acids include succinicacid, adipic acid, sebacic acid and so on. Also, favorable examples ofthe alkenylene dicarboxylic acids include those having 4 to 20 carbonatoms such as maleic acid, fumaric acid and so on. Also, favorableexamples of the aromatic dicarboxylic acids include those having 8 to 20carbon atoms such as phthalic acid, isophthalic acid, terephthalic acid,naphthalenedicarboxylic acid and so on. Among these, the alkenylenedicarboxylic acids having 4 to 20 carbon atoms and the aromaticdicarboxylic acids having 8 to 20 carbon atoms are preferable.

As the polycarboxylic acids having 3 or more valences (TC), those having3 to 8 valences or greater are preferable, and examples thereof includearomatic polycarboxylic acids and so on. Also, as the aromaticpolycarboxylic acid, those having 9 to 20 carbon atoms are preferable,and examples thereof include trimellitic acid, pyromellitic acid and soon.

As the polycarboxylic acids (PC), it is possible to use acid anhydridesor lower alkyl esters of any one selected from the dicarboxylic acid(DIC), the polycarboxylic acid having 3 or more valences (TC), and amixture of the dicarboxylic acid (DIC) and the polycarboxylic acidhaving 3 or more valences. Examples of the lower alkyl esters includemethyl esters, ethyl esters, isopropyl esters and so on.

A mixing mass ratio (DIC:TC) of the dicarboxylic acid (DIC) and thepolycarboxylic acid having 3 or more valences (TC) in the mixture of thedicarboxylic acid (DIC) and the polycarboxylic acid having 3 or morevalences (TC) is not particularly restricted, and it may beappropriately selected according to purpose. For example, it ispreferably 100:0.01 to 10, and more preferably 100:0.01 to 1.

A mixing ratio in a polycondensation reaction of the polyol (PO) and thepolycarboxylic acid (PC) is not particularly restricted, and it may beappropriately selected according to purpose. For example, an equivalentratio ([OH]/[COOH]) of a hydroxyl group [OH] in the polyol (PO) and thecarboxyl group [COOH] in the polycarboxylic acid (PC) is preferably 2/1to 1/1, more preferably 1.5/1 to 1/1, and further preferably 1.3/1 to1.02/1.

A content of the polyol (PO) in the isocyanate group-containingpolyester prepolymer (A) is not particularly restricted, and it may beappropriately selected according to purpose. For example, it ispreferably 0.5% by mass to 40% by mass, more preferably 1% by mass to30% by mass, and further preferably 2% by mass to 20% by mass. When thecontent is less than 0.5% by mass, hot-offset resistance degrades, andit may become difficult to obtain both heat-resistant storage stabilityand low-temperature fixing property of the toner. When it exceeds 40% bymass, low-temperature fixing property may degrade.

The polyisocyanate (PIC) is not particularly restricted, may beappropriately selected according to purpose. Examples thereof includealiphatic polyisocyanates, alicyclic polyisocyanates, aromaticpolyisocyanates, aromatic aliphatic diisocyanates, isocyanurates, andthose blocked by phenol derivatives, oximes, caprolactams and so on.

Examples of the aliphatic polyisocyanates include tetramethylenediisocyanate, hexamethylene diisocyanate, 2,6-diisocyanatomethylcaproate, octamethylene diisocyanate, decamethylene diisocyanate,dodecamethylene diisocyanate, tetradecamethylene diisocyanate,trimethylhexane diisocyanate, tetramethylhexane diisocyanate and so on.Also, examples of the alicyclic polyisocyanates include isophoronediisocyanate, cyclohexyl diisocyanate and so on. Also, examples of thearomatic polyisocyanatea include tolylene diisocyanate, diphenylmethanediisocyanate, 1,5-1,5-naphthylene diisocyanate,diphenylene-4,4′-diisocyanate, 4,4′-diisocyanato-3,3′-dimethyldiphenyl,3-methyldiphenylmethane-4,4′-diisocyanate, diphenylether-4,4′-diisocyanate and so on. Also, examples of the aromaticaliphatic diisocyanates include α,α,α′,α′-tetramethylxylylenediisocyanate and so on. Also, examples of the isocyanurates includetris-isocyanatoalkyl-isocyanurate, triisocyanatocycloalkyl-isocyanurateand so on. These may be used alone or in combination of two or more.

As a mixing ratio in reacting the polyisocyanate (PIC) and the polyesterresin having an active hydrogen group having an active hydrogen group(e.g. hydroxyl group-containing polyester resin), a mixing equivalentratio ([NCO]/[OH]) of an isocyanate group [NCO] in the polyisocyanate(PIC) and a hydroxyl group [OH] in the hydroxyl group-containingpolyester resin is preferably 5/1 to 1/1, more preferably 4/1 to 1.2/1,and further preferably 3/1 to 1.5/1. When the mixing equivalent ratio([NCO]/[OH]) exceeds 5, low-temperature fixing property may degrade.When it is less than 1, offset resistance may degrade.

A content of the polyisocyanate (PIC) in the isocyanate group-containingpolyester prepolymer (A) is not particularly restricted, and it may beappropriately selected according to purpose. Nonetheless, it ispreferably 0.5% by mass to 40% by mass, more preferably 1% by mass to30% by mass, and further preferably 2% by mass to 20% by mass. When thecontent is less than 0.5% by mass, hot-offset resistance degrades, andit may become difficult to obtain both heat-resistant storage stabilityand low-temperature fixing property. When it exceeds 40% by mass,low-temperature fixing property degrades.

An average number of the isocyanate group included in one molecule ofthe isocyanate group-containing polyester prepolymer (A) is preferably 1or greater, more preferably 1.2 to 5, and further preferably 1.5 to 4.When the average number of the isocyanate group is less than 1, thepolyester resin modified with a urea bond-forming group (RMPE) has adecreased molecular weight, resulting in degraded hot-offset resistance.

A weight-average molecular weight (Mw) of the binder resin precursorhaving a site capable of reacting with the compound having an activehydrogen group is, as a molecular-weight distribution by GPC (gelpermeation chromatography) of a tetrahydrofuran (THF)-soluble content,preferably 3,000 to 40,000, and more preferably 4,000 to 30,000. Whenthe weight-average molecular weight (Mw) is less than 3,000,heat-resistant storage stability may degrade. When it exceeds 40,000,low-temperature fixing property may degrade.

A measurement of the molecular-weight distribution by gel permeationchromatography (GPC) may be carried out as follows, for example. First,a column is stabilized in a heat chamber at 40° C. At this temperature,tetrahydrofuran (THF) as a column medium is flown at a flow rate of 1mL/min. Then, 50 μL to 200 μL of a tetrahydrofuran sample solution of aresin with the sample concentration adjusted to 0.05% by mass to 0.6% bymass is injected, and measurement is taken. Regarding the measurement ofa molecular weight of the sample, a molecular-weight distribution of thesample is calculated from a relation between logarithms of a calibrationcurve created by several types of monodispersed polystyrene standardsamples and the number of count. As the standard polystyrene samples forcreating the calibration curve, samples having a molecular weight of6×10², 2.1×10², 4×10², 1.75×10⁴, 1.1×10⁵, 3.9×10⁵, 8.6×10⁵, 2×10⁶ and4.48×10⁶, for example, manufactured by Pressure Chemical Co. or TosohCorporation are used, and it is appropriate to use at least 10 standardpolystyrene samples. As a detector, an RI (Refractive Index) detectormay be used.

<<Releasing Agent>>

The releasing agent is not particularly restricted and may beappropriately selected according to purpose. Nonetheless, a releasingagent having a low melting point that the melting point is 50° C. to120° C. The releasing agent having a low melting point dispersed withthe resin works effectively as a releasing agent between a fixing rollerand a toner interface, and thereby hot offset property is favorable evenin an oil-less operation (a releasing agent such as oil is not appliedon a fixing roller).

As the releasing agent, for example, waxes are favorable. Examples ofthe waxes include natural waxes including: vegetable waxes such ascarnauba wax, cotton wax, japan wax, rice wax and so on; animal waxessuch as bees wax, lanolin and so on; mineral waxes such as ozokerite,ceresin and so on; petroleum waxes such as paraffin, microcrystallinewax, petrolatum and so on; and so on. Also, other than these naturalwaxes, examples further include: synthetic hydrocarbon waxes such asfischer-tropsch wax, polyethylene wax and so on; synthetic waxes such asesters, ketones, ethers and so on; and so on. Further, it is alsopossible to use: fatty acid amides such as 12-hydroxy stearic amide,stearic amide, phthalic anhydride imide, chlorinated hydrocarbons and soon; homopolymers or copolymers of polyacrylates such as poly-n-stearylmethacrylate, poly-n-lauryl methacrylate and so on as alow-molecular-weight crystalline polymeric resin (for example, acopolymer of n-stearyl acrylate and ethyl methacrylate and so on); andcrystalline polymers having a long alkyl group in a side chain thereof.These may be used alone or in combination of two or more.

A melting point of the releasing agent is not particularly restricted,and it may be appropriately selected according to purpose. Nonetheless,it is preferably 50° C. to 120° C., and more preferably 60° C. to 90° C.When the melting point is less than 50° C., the wax may adversely affectheat-resistant storage stability. When it exceeds 120° C., it is likelyto cause cold offset during fixing at a low temperature. A meltviscosity of the releasing agent is, as a measured value at atemperature higher by 20° C. than the melting point of the wax,preferably 5 cps to 1,000 cps, and more preferably 10 cps to 100 cps.When the melt viscosity is less than 5 cps, releasing property maydegrade. When it exceeds 1,000 cps, effects of improved hot-offsetresistance and low-temperature fixing property may not be obtained. Acontent of the releasing agent in the toner is not particularlyrestricted, and it may be appropriately selected according to purpose.Nonetheless, it is preferably 0% by mass to 40% by mass, and morepreferably 3% by mass to 30% by mass. When the content exceeds 40% bymass, fluidity of the toner may degrade.

<<Other Components>>

The other components are not particularly restricted and may beappropriately selected according to purpose. Examples thereof include acolorant, a charge controlling agent, inorganic fine particles, afluidity improving agent, a cleanability improving agent, a magneticmaterial, a metal soap and so on.

<<<Colorant>>>

The colorant for the toner used in the present invention is notparticularly restricted, and it may be appropriately selected fromheretofore known dyes and pigments according to purpose. Examplesthereof include carbon black, nigrosine dye, iron black, naphthol yellowS, Hansa Yellow (10G, 5G, G), cadmium yellow, yellow iron oxide, yellowocher, chrome yellow, titanium yellow, polyazo yellow, Oil Yellow, HansaYellow (GR, A, RN, R), Pigment Yellow L, Benzidine Yellow (G, GR),Permanent Yellow (NCG), Vulcan Fast Yellow (5G, R), tartrazine lake,quinoline yellow lake, Anthrazane Yellow BGL, isoindolinone yellow,colcothar, red lead, lead vermilion, cadmium red, Cadmium Mercury Red,antimony vermilion, Permanent Red 4R, Para Red, fiser red,para-chloro-ortho-nitroaniline red, Lithol Fast Scarlet G, BrilliantFast Scarlet, Brilliant Carmine BS, Permanent. Red (F2R, F4R, FRL, FRLL,F4RH), Fast Scarlet VD, Vulcan Fast Rubine B, Brilliant Scarlet G,Lithol Rubine GX, Permanent Red FSR, Brilliant Carmine 6B, PigmentScarlet 3B, Bordeaux 5B, Toluidine Maroon, Permanent Bordeaux F2K, HelioBordeaux BL, Bordeaux 10B, BON Maroon Light, BON Maroon Medium, EosinLake, Rhodamine Lake B, Rhodamine Lake Y, Alizarine Lake, Thioindigo RedB, Thioindigo Maroon, Oil Red, Quinacridone Red, Pyrazolone Red, polyazored, Chrome Vermilion, Benzidine Orange, perynone orange, Oil Orange,cobalt blue, cerulean blue, Alkali Blue Lake, Peacock Blue Lake,Victoria Blue Lake, metal-free Phthalocyanine Blue, Phthalocyanine Blue,Fast Sky Blue, Indanthrene Blue (RS, BC), Indigo, ultramarine, Prussianblue, Anthraquinone Blue, Fast Violet B, Methyl Violet Lake, cobaltviolet, manganese violet, dioxane violet, Anthraquinone Violet, ChromeGreen, zinc green, chromium oxide, viridian, emerald green, PigmentGreen B, Naphthol Green B, Green Gold, Acid Green Lake, Malachite GreenLake, phthalocyanine green, anthraquinone green, titanium oxide, zinc,oxide, lithopone and so on. These may be used alone or in combination oftwo or more.

A content of the colorant in the toner is not particularly restricted,and it may be appropriately selected according to purpose. Nonetheless,it is preferably 1% by mass to 15% by mass, and more preferably 3% bymass to 10% by mass. When the content of the colorant is less than 1% bymass, coloring strength may degrade. When it exceeds 15% by mass, poordispersion of the pigment in the toner occurs, which may cause decreasedcoloring strength and decreased electrical characteristics of the toner.

The colorant may also be used as a masterbatch combined with a resin.The resin is not particularly restricted, and it may be appropriatelyselected from heretofore known ones according to purpose. Examplesthereof include polyester, a polymer of styrene or substituent thereof,a styrene copolymer, polymethyl methacrylate, polybutyl methacrylate,polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, anepoxy resin, an epoxy polyol resin, polyurethane, polyamide, polyvinylbutyral, polyacrylic acid, rosin, modified rosin, a terpene resin, analiphatic hydrocarbon resin, an alicyclic hydrocarbon resin, an aromaticpetroleum resin, chlorinated paraffin, paraffin wax, and so on. Thesemay be used alone or in combination of two or more.

Examples of the polymer of styrene or substituent thereof include apolyester resin, polystyrene, poly-p-chlorostyrene, polyvinyltoluene,and so on. Examples of the styrene copolymer include astyrene-p-chlorostyrene copolymer, a styrene-propylene copolymer, astyrene-vinyltoluene copolymer, a styrene-vinylnaphthalene copolymer, astyrene-methyl acrylate copolymer, a styrene-ethyl acrylate copolymer, astyrene-butyl acrylate copolymer, a styrene-octyl acrylate copolymer, astyrene-methyl methacrylate copolymer, a styrene-ethyl methacrylatecopolymer, a styrene-butyl methacrylate copolymer, a styrene-α-methylchloromethacrylate copolymer, a styrene-acrylonitrile copolymer, astyrene-vinyl methyl ketone copolymer, a styrene-butadiene copolymer, astyrene-isoprene copolymer, a styrene-acrylonitrile-indene copolymer, astyrene-maleic acid copolymer, a styrene-maleic acid ester copolymer,and so on.

The masterbatch is manufactured by mixing or kneading the resin formasterbatch and the colorant with an application of high shear force. Atthis time, to enhance an interaction between the colorant and the resinfor masterbatch, an organic solvent is preferably used. Also, aso-called flushing method is favorably used since a wet cake of thecolorant may be used as it is, without necessity of drying. Thisflushing method is a method of mixing or kneading an aqueous paste ofthe colorant including water with the resin for masterbatch and anorganic solvent to remove the water and the organic medium bytransferring the colorant to the resin for masterbatch. For the mixingor kneading, for example, a high shear dispersing apparatus such asthree-roll mill is favorably used.

<<<Charge Controlling Agent>>

The charge controlling agent is not particularly restricted, and it maybe appropriately selected from heretofore known ones according topurpose. Examples thereof include nigrosine dyes, triphenylmethane dyes,chromium-containing metal complex dyes, molybdic acid chelate pigments,rhodamine dyes, alkoxy amines, quaternary ammonium salt (includingfluorine-modified quaternary ammonium salts), alkyl amides, elementalphosphorus or phosphorus compound, elemental tungsten or tungstencompounds, fluorine surfactants, metal salts of salicylic acid, metalsalts of salicylic acid derivatives, and so on. These may be used aloneor in combination of two or more.

Commercial products may be used as the charge controlling agent.Examples of the commercial products include: BONTRON 03 of nigrosinedyes, BONTRON P-51 of quaternary ammonium salt, BONTRON S-34 ofmetal-containing azo dye, E-82 of oxynaphthoic acid metal complex, E-84of salicylic acid metal complex, E-89 of phenol condensate (manufacturedby Orient Chemical Industries Co., Ltd.); TP-302, TP-415 of quaternaryammonium salt molybdenum complexes (manufactured by Hodogaya ChemicalCo., Ltd.); Copy charge PSY VP2038 of quaternary ammonium salt, Copyblue PR of triphenylmethane derivative, Copy charge NEG VP2036, Copycharge NX VP434 of quaternary ammonium salts (manufactured by Clariant(Japan) KK); LRA-901, LR-147 as a boron complex (manufactured by CarlitJapan Co., Ltd.); copper phthalocyanine, perylene, quinacridone, azopigments, other polymeric compounds having functional groups such assulfonic acid group, carboxyl group, quaternary ammonium salt and so on,and so on.

By incorporating the charge controlling agent selectively in a resinphase of the toner particles main body existing in an inner layer, it ispossible to suppress spent charge controlling agent on other memberssuch as photoconductor, carrier and so on. In the toner manufacturingmethod of the present invention, there are cases where an arrangement ofthe charge controlling agent is relatively freely designed, and it ispossible to take a desired arrangement in accordance with respectiveimage forming processes.

A content of the charge controlling agent in the toner varies dependingon the types of the resins, presence or absence of the externaladditive, dispersion methods and so on, and it cannot be unambiguouslydefined. Nonetheless, it is preferably 0.1 parts by mass to 10 parts bymass, and more preferably 0.2 parts by mass to 5 parts by mass withrespect to 100 parts by mass of the binder resin. When the content ofthe charge controlling agent is less than 0.1 parts by mass,charge-controlling property may not be obtained. When it exceeds 10parts by mass, charging property of the toner becomes excessive. Thisweakens an effect of the main charge controlling agent and increaseselectrostatically attractive force with a developing roller, which mayresult in reduced fluidity of a developer and reduced image density.

<<<Fluidity Improving Agent>>>

The fluidity improving agent is defined as an agent for surfacetreatment to increase hydrophobicity in order to prevent degradation offluidity properties and charge properties even under high-humiditycondition. Examples thereof include a silane coupling agent, asilylating agent, a silane coupling agent having a fluorinated alkylgroup, an organic titanate coupling agent, an aluminum-based couplingagent, a silicone oil, a modified silicone oil, and so on. It isparticularly preferable to use silica and titanium oxide as hydrophobicsilica and hydrophobic titanium oxide by surface treatment thereof withsuch a fluidity improving agent.

<<<Cleanability Improving Agent>>>

The cleanability improving agent is added to the toner in order toremove a developer which remains on a photoconductor or a primarytransfer medium after transfer. Examples thereof include: fatty acidmetal salts of stearic acid and so on such as zinc stearate and calciumstearate; polymer particles manufactured by soap-free emulsionpolymerization of polymethyl methacrylate fine particles, polystyrenefine particles and so on. The polymer particles preferably have arelatively narrow particle size distribution, and those having avolume-average particle diameter of 0.01 μm to 1 μm are preferable.

<<<Layered Inorganic Mineral>>>

A layered inorganic mineral may be included in the toner according tonecessity. The layered inorganic mineral is an inorganic mineralcomposed of layers with a thickness of several nm, and modification withan organic ion is to introduce an organic ion to ions existing betweenthe layers. It is specifically described in JP-A No. 2003-515795, JP-ANo. 2006-500605 and JP-A No. 2006-503313. This is broadly called asintercalation. As the layered inorganic mineral, a smectite group(montmorillonite, saponite and so on), a kaolin group (kaolinite and soon), magadiite, and kanemite are known. The modified layered inorganicmineral is highly hydrophilic due to its modified layered structure.Accordingly, when the layered inorganic mineral is used withoutmodification for a granulated toner produced by dispersion in an aqueousmedium, the layered inorganic mineral migrates in the aqueous medium,and it is impossible to deform the toner. However, hydrophilicityincreases by modification, and the modified layered inorganic mineral isrefined as well as deformed during toner manufacturing. It existsparticularly at a surface portion of the toner particles, and it plays acharge-control function and contributes to low-temperature fixing. Atthis time, a content of the modified layered inorganic mineral in thetoner materials is preferably 0.05% by mass to 5% by mass.

The modified layered inorganic mineral used in the present invention ispreferably a smectite having a basic crystal structure modified with anorganic cation. Also, by substituting a part of a divalent metal of thelayered inorganic mineral by a trivalent metal, a metal anion may beintroduced. However, since introduction of the metal anion increaseshydrophilicity, layered inorganic compound that a part of the metalanion is modified with an organic anion is preferable.

Regarding the layered inorganic mineral including ions at leastpartially modified with an organic ion, examples of an organic-ionmodifying agent of the layered inorganic mineral include quaternaryalkylammonium salts, phosphonium salts, imidazolium salts and so on, andthe quaternary alkylammonium salts are preferable. Examples of thequaternary alkylammonium include trimethylstearylammonium,dimethylstearylbenzylammonium, dimethylactadecylammonium, oleylbis(2-hydroxyethyl)methylammonium and so on.

Examples of the organic-ion modifying agent further include sulfates,sulfonates, carboxylates and phosphates inducing branched, non-branchedor cyclic alkyl (C1 to C44), alkenyl (C1 to C22), alkoxy (C8 to C32),hydroxyalkyl (C2 to C22), ethylene oxide, propylene oxide and so on. Acarboxylic acid having an ethylene oxide skeleton is preferable.

The layered inorganic mineral at least partially modified with anorganic ion has moderate hydrophobicity. Thus, the oil phase includingthe toner composition and/or the toner composition precursor has anon-Newtonian viscosity, and the toner may be deformed. At this time, acontent of the layered inorganic mineral partially modified with anorganic ion in the toner materials is preferably 0.05% by mass to 5% bymass.

The layered inorganic mineral partially modified with an organic ion maybe appropriately selected, and examples thereof include montmorillonite,bentonite, hectorite, attapulgite, sepiolite, mixtures thereof and soon. Among these, organically modified montmorillonite or bentonite ispreferable since it allows easier viscosity control only with a smallamount without affecting toner properties.

Examples of commercial products of the layered inorganic mineralpartially modified with an organic cation include: quaternium-18bentonite such as Benton 3, Bentone 38, Benton 38V (manufactured byRheox Corporation), TIXOGEL VP (manufactured by United Catalyst),CLAYTON 34, CLAYTON 40, CLAYTON XL (manufactured by Southern ClayProducts, Inc.) and so on; stearalkonium bentonite such as Bentone 27(manufactured by Rheox Corporation), TIXOGEL LG (manufactured by UnitedCatalyst), CLAYTON AF, CLAYTON APA (manufactured by Southern ClayProducts, Inc.) and so on; quaternium-18/benzalkonium bentonite such asCLAYTON HT, CLAYTON PS (manufactured by Southern Clay Products, Inc.)and so on. CLAYTON AF and CLAYTON APA are particularly preferable. Also,as a layered inorganic mineral partially modified with an organic anion,DHT-4A (manufactured by Kyowa Chemical Industry Co., Ltd.) modified withan organic anion represented by General Formula (3) below isparticularly preferable. Exemplary compounds of General Formula (3)include HITENOL 330T (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.).

R₁(OR₂)nOSO₃M  General Formula (3)

[In the formula, R₁ represents an alkyl group having 13 carbon atoms; R₂represents an alkylene group having 2 to 6 carbon atoms; n represents aninteger of 2 to 10; M represents a monovalent metal element.]

The modified layered inorganic mineral provides appropriatehydrophobicity. In a manufacturing process of the toner including this,the oil phase including the toner composition has a non-Newtonianviscosity, and the toner may be deformed.

<Inorganic Fine Particles>

The inorganic fine particles includes at least inorganic fine particles(A) which are each a secondary particle where a plurality of primaryparticles are coalesced together, and it further includes otherinorganic fine particles according to necessity.

The inorganic fine particles are used as an external additive forimparting fluidity, developing property, charging property and so on tothe toner particles. It is important that these inorganic fine particlesinclude the inorganic fine particles (A) which are each a secondaryparticle where a plurality of primary particles are coalesced together.

<<Inorganic Fine Particles (A)>>

The primary particles of the inorganic fine particles (A) are notparticularly restricted, and they may be appropriately selected fromheretofore known ones according to purpose. Examples thereof includesilica, alumina, titanium oxide, barium titanate, magnesium titanate,calcium titanate, strontium titanate, zinc oxide, tin oxide, silicasand, clay, mica, wollastonite, diatomaceous earth, chromium oxide,cerium oxide, colcothar, antimony trioxide, magnesium oxide, zirconiumoxide, barium sulfate, barium carbonate, calcium carbonate, siliconcarbide, silicon nitride and so on. These may be used alone or incombination of two or more. Among these, silica is preferable.

As the inorganic fine particles (A), coalesced silica is preferable.

The coalesced silica is secondary aggregated silica obtained bychemically bonding primary particles of silica and/or fused silica usinga treating agent.

The coalesced silica used in the present invention is prepared bychemically bonding primary particles of crystalline silica and/or fusedsilica using a treating agent, and as the treating agent, a silane-basedagent such as alkoxysilanes, silane coupling agents, chlorosilanes,silazanes and so on or an epoxy-based treating agent such as liquidepoxy resin are favorably used.

When primary silica particles are processed using the silane-based agentsuch as alkoxysilanes, silane coupling agent and so on, a silanol groupbonded to the primary silica particles and an alkoxy group bonded to thesilane-based agent react, and a Si—O—Si bond is newly formed bydealcoholization.

That is, the primary silica particles form secondary aggregation bychemical bonding via the silane-based agent as indicated in the formulabelow.

When the primary silica particles are processed using the chlorosilanes,a chloro group of the chlorosilanes and a silanol group bonded to theprimary silica particles newly forms a Si—O—Si bond by adehydrochlorination reaction. Also, in case water co-exists in thesystem, the chlorosilanes is hydrolyzed in water to form a silanol groupand then the silanol group and a silanol group bonded to the primarysilica particles newly forms a Si—O—Si bond by a dehydration reaction.Thereafter, secondary aggregation occurs.

Also, as for the silazanes, an amino group and a silanol group bonded tothe primary silica particles undergo deammoniation to newly form aSi—O—Si bond, followed by secondary aggregation.

Meanwhile, when the primary silica particles is processed using theepoxy-based treating agent, a silanol group bonded to the primary silicaparticles adds an oxygen atom of the epoxy group and a carbon atombonded to the epoxy group of the epoxy-based treating agent and newlyforms a Si—O—C bond.

That is, the primary silica particles form secondary aggregation bychemical bonding via the epoxy-based treating agent as indicated in theformula below.

The coalesced silica used in the present invention is produced bypreparation of silica as primary particles followed by a process usingthe silane-based agent or the epoxy-based treating agent, and it may beused as a filler of an epoxy resin. Also, when silica is synthesized bya sol-gel method, the coalesced silica may be prepared in a one-stepreaction by allowing the silane-based agent or the epoxy-based treatingagent to co-exist.

Also, regarding use as the treating agent, since the generated Si—O—Sibond is more stable against heat than the Si—O—C bond, the silane-basedagent is more preferable than the epoxy-based treating agent. Specificexamples of the alkoxysilanes as the silane-based agent includetetramethoxysilane, tetraethoxysilane, methyltrimethoxysilane,methyltriethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane,methyldimethoxysilane, methyldiethoxysilane, diphenyldimethoxysilane,isobutyltrimethoxysilane, decyltrimethoxysilane and so on.

Also, specific examples of the silane coupling agent as the abovesilane-based agent include γ-aminopropyltriethoxysilane,γ-glycidoxypropyltrimethoxysilane,γ-glycidoxypropylmethyldiethoxysilane,γ-methacryloxypropyltrimethoxysilane, γ-mercaptnpropyltrimethoxysilane,vinyltriethoxysilane, methylvinyldimethoxysilane and so on.

Further, specific examples of the silane-based agent other than thealkoxysilanes or the silane coupling agent include vinyltrichlorosilane,dimethyldichlorosilane, methylvinyldichlorosilane, methyl phenyldichlorosilane, phenyltrichlorosilane, N,N′-bis(trimethylsilyl)urea,N,O-bis(trimethylsilyl)acetamide, dimethyl trimethylsilyl amine,hexamethyldisilazane, cyclicsilazane mixture and so on.

Specific examples of the epoxy-based treating agent include a bisphenolA epoxy resin, a bisphenol F epoxy resin, a phenol novolak epoxy resin,a cresol novolak epoxy resin, a bisphenol A novolak epoxy resin, abiphenol epoxy resin, a glycidyl amine epoxy resin, an alicyclic epoxyresin and so on.

The coalesced silica used in the present invention is prepared bychemically bonding primary particles of the crystalline silica and/orthe fused silica using the treating agent, and as the process, theprimary silica particles and the treating agent are mixed using aheretofore known mixer such as spray dryer and so on at a mass ratio of100:0.01 to 100:50.

At this time, as a processing aid, for example, water, a 1-% acetic acidaqueous solution and so on may be appropriately added.

A mixture of the primary silica particles and the treating agent is thenbaked, and a baking temperature thereof is selected from a temperaturerange of 100° C. to 2500° C.

Also, a baking time is 0.5 hours to 30 hours.

A degree of coalescence of silica may be arbitrarily controlled byvarying primary particle diameter, types and amounts of the treatingagent, and processing conditions.

That is, an aggregation force is stronger by using the silane-basedagent rather than the epoxy-based treating agent, by increasing anamount of the treating agent with respect to the primary silicaparticles, or by increasing the baking temperature, respectively, andthe degree of coalescence tends to be higher. On the other hand, byincreasing the baking time, a proportion of non-coalesced particles maybe reduced. However, excessive extension of time promotes aggregationbetween coalesced particles, and there is a possibility of a problem onan adhesive property to the toner.

An amount of the inorganic fine particles (A) added with respect to 100parts by mass of the toner is preferably 1.0 part by mass to 3.0 partsby mass, and more preferably 1.5 parts by mass to 2.5 parts by mass.When it is less than 1.0 parts by mass, a sufficient spacer effectcannot be obtained, and it is difficult to suppress embedding byexternal stresses. On the other hand, when it exceeds 3.0 parts by mass,there is a concern that an amount of withdrawal increases, causingdefects such as photoconductor filming and phenomenon of vibratingcleaning blade (a so-called chatter vibration) and so on.

Also, the inorganic fine particles (A) have Db₅₀/Db₁₀ in a particle sizedistribution of a secondary particle diameter Db of preferably 1.20 orless, and more preferably 1.15 or less. Here, Db₅₀ represents a particlediameter at which a cumulative percentage of the secondary particlediameter measured from a side of smaller particles and observed by anFE-SEM is 50% by number, and Db₁₀ represents a particle diameter atwhich the cumulative percentage measured from the side of smallerparticles is 10% by number.

Db₅₀/Db₁₀ represents a proportion of particles having a smallersecondary particle diameter and median particles. A large value thereofindicates there are many particles having a smaller secondary particlediameter. That is, it means that there are many particles A existing asprimary particles with coalescence not progressed, or there are manyparticles B with coalescence progressed but composed of primaryparticles themselves having a small particle diameter, or both thereof.Such particles A or B respectively do not have sufficient features. Theparticles A cannot completely fulfill a function as the deformedexternal additive and is inferior in terms of resistance to embedding,and thus there is a concern of occurrences of an abnormal image. On theother hand, the particles B cannot completely fulfill a function of thespacer effect, and it is unlikely to suppress embedding by externalstresses. It is preferable to reduce these particles, or in other words,to have a large value of Db₁₀. When Db₅₀/Db₁₀ exceeds 1.2, the particlesA and B are in abundance, and it becomes difficult to fulfill thefunction as the deformed external additive characterized for suppressionof embedding.

Also, when a ratio (Db/Da) with Db being the secondary particle diameterof the inorganic fine particles (A) and Da being an average primaryparticle diameter of a plurality of primary particles forming theinorganic fine particles (A) is defined as the degree of coalescence ofthe inorganic fine particles (A), an average of the degrees ofcoalescence G is not particularly restricted and may be appropriatelyselected according to purpose. Nonetheless, it is preferably in a rangeof 1.5 to 4.0, and more preferably 2.0 to 3.0.

When the degree of coalescence G is less than 1.5, a function tomaintain high transfer property is slightly inferior. This is becausethe external additive is likely to be embedded in the base and theexternal additive is likely to roll into concave portions. Also, thetoner with the degree of coalescence exceeding 4.0 is slightly weak interms of degradation over time. This is because the external additive islikely to be exfoliated from the toner, causing carrier contamination orscratches on a photoconductor.

Also, a content of inorganic fine particles (A) with the degree ofcoalescence G of less than 1.3 in the inorganic fine particles (A) isnot particularly restricted, and it may be appropriately selectedaccording to purpose. Nonetheless, it is preferably 10% by number orless.

The degree of coalescence G has a distribution due to its manufacturingnature. Particles having the degree of coalescence of less than 1.3 areparticles with coalescence not progressed, existing in an almostspherical state. Accordingly, it is difficult to fulfill the function asthe deformed external additive characterized for suppressing embedding.

Also, an average secondary particle diameter of the coalesced silica Dbais not particularly restricted, and it may be appropriately selectedaccording to purpose. Nonetheless, it is preferably 80 nm to 200 nm, andmore preferably 100 nm to 160 nm. When it is less than 80 nm, the silicabecomes difficult to fulfill the function as the spacer effect anddifficult to suppress embedding by external stresses. On the other hand,when it exceeds 200 nm, the silica is easily freed from the toner,causing photoconductor filming.

[Method for Measuring Properties of Inorganic Fine Particles]<Measurement of Degree of Coalescence>

The degree of coalescence is measured by an image observation. Theinorganic fine particles (A) are dispersed in an appropriate solvent(THF and so on), and then the sample on a substrate with the solventremoved to dryness is observed by FE-SEM. With an accelerating voltageof 5 kV to 8 kV and an observation magnification of 8 k to 10 k, thesecondary particle diameter of the inorganic fine particles (A) in afield of view is measured. As the secondary particle diameter, a maximumlength of aggregated particles is measured. FIG. 5 illustrates oneexample.

The primary particle diameter is similarly observed by FE-SEM. Anoverall image of embedded particles is predicted from an outline of thecoalesced inorganic fine particles (A), and a maximum length of theoverall image is measured. FIG. 6 illustrates one example. The secondaryparticle diameter of one inorganic fine particle (A) and an average ofthe primary particle diameter of a plurality of primary particlescoalesced in the inorganic fine particles are obtained, and the degreeof coalescence is determined.

Degree of coalescence=secondary particle diameter/average primaryparticle diameter

Observations are made for 100 or more inorganic fine particles (A) toobtain the degree of coalescence of the respective particles, and anaverage of the degree of coalescence and a ratio of the inorganic fineparticles (A) having a degree of coalescence of less than 1.3 areobtained.

By the above measurement method, the particle size distribution of thesecondary particle diameter is obtained, and further Db₅₀ and Db₁₀ arecalculated.

<<Other Inorganic Fine Particles>>

Other inorganic fine particles may be used in combination in the tonerof the present invention for assisting fluidity, developing property andcharging property.

The inorganic fine particles used in combination has a primary particlediameter of preferably 5 nm to 70 nm, and more preferably 5 nm to 50 nm.A proportion of these inorganic fine particles is preferably 0.01% bymass to 5% by mass, and more preferably 0.01% by mass to 2.0% by mass ofthe toner.

Examples of the other inorganic fine particles include silica, alumina,titanium oxide, barium titanate, magnesium titanate, calcium titanate,strontium titanate, zinc oxide, tin oxide, silica sand, clay, mica,wollastonite, diatomaceous earth, chromium oxide, cerium oxide,colcothar, antimony trioxide, magnesium oxide, zirconium oxide, bariumsulfate, barium carbonate, calcium carbonate, silicon carbide, siliconnitride and so on.

[Method for Manufacturing Toner]

A toner manufacturing method of the present invention is notparticularly restricted, may be appropriately selected according topurpose. Examples thereof include a pulverization method, polymerizationmethods such as emulsion-aggregation method and dissolution-suspensionmethod and so on. The dissolution-suspension method is preferably usedin order to obtain a toner having a small particle diameter and a smallDv/Dn.

The toner of the present invention is preferably a toner obtained bygranulation in an aqueous medium. A toner produced by obtaining anemulsified dispersion by dispersing in an aqueous medium an oil phaseobtained by dissolving or dispersing toner materials including at leasta polyester resin, a colorant and a releasing agent in an organicsolvent and by removing the organic solvent from the emulsifieddispersion. A particularly favorable toner is produced by obtaining anemulsified dispersion by dispersing in an aqueous medium an oil phaseobtained by dissolving or dispersing toner materials including at leasta compound having an active hydrogen group, the binder resin precursorhaving a site capable of reacting with a compound having an activehydrogen group, a polyester resin, a colorant and a releasing agent, byreacting the binder resin precursor and the compound having an activehydrogen group in the emulsified dispersion and by removing the organicsolvent.

As the respective manufacturing methods, a toner is manufacturedspecifically as follows.

The pulverization method is a method to obtain base particles of thetoner by, for example, melting or kneading toner materials followed bypulverization, classification and so on.

Here, in the pulverization method, a mechanical impact may be applied tocontrol a shape of the obtained toner base particles obtained for thepurpose that the toner has an average circularity in a range of 0.97 to1.0.

In this case, the mechanical impact may be applied to the toner baseparticles using devices such as hybridizer, mechanofusion and so on.

An aqueous granulated toner may be manufactured by theemulsion-aggregation method or the dissolution-suspension method asfollows.

<Emulsion-Aggregation Method>

There is an emulsion-polymerization-aggregation method as a method toproduce a toner by dispersing and/or emulsifying an oil phase or amonomer phase including at least a toner composition or a tonercomposition precursor in an aqueous medium for granulation.

In the emulsion-polymerization-aggregation-fusion method includes: astep for preparing an aggregated-particle dispersion liquid by mixing aresin-particle dispersion liquid prepared by an emulsion polymerizationmethod, a separately prepared layered inorganic mineral at leastpartially modified with an organic ion, a colorant dispersion liquid,and a releasing-agent dispersion liquid according to necessity foraggregating at least the resin particles, the layered inorganic mineralat least partially modified with an organic ion and the colorant to formaggregated particles (hereinafter, it may also be referred to as an“aggregation step”); and a step for forming toner particles by heatingand fusing the aggregated particles (hereinafter, it may also bereferred to as a “fusing step”).

In the aggregation step, the resin-particle dispersion liquid, thelayered inorganic mineral at least partially modified with an organicion, the colorant dispersion liquid and the releasing-agent dispersionliquid according to necessity are mixed with one another, and byaggregating the resin particles and so on to form the aggregatedparticles. The aggregated particles are formed by heteroaggregation andso on, and at that time, it is possible to add an ionic surfactanthaving a different polarity from the aggregated particles or a compoundhaving a charge of one or more valences such as such as metal salts forthe purpose of stabilization and control of the particlediameter/particle size distribution of the aggregated particles. In thefusing step, the aggregated particles are heated to a temperature of theglass transition temperature of resins in the aggregated particles orgreater for fusion.

Before the fusing step, it is possible to arrange an adhesion step,wherein a dispersion liquid of other fine particles is added and mixedto the aggregated-particle dispersion liquid for uniformly adhering fineparticles on a surface of the aggregated particles to form adheredparticles. Further, it is possible to arrange an adhesion step, whereina dispersion liquid of the layered inorganic mineral at least partiallymodified with an organic ion is added and mixed in theaggregated-particle dispersion liquid for uniformly adhering the layeredinorganic mineral at least partially modified with an organic ion on asurface of the aggregated particles to form adhered particles. Also, inorder to strengthen the adhesion of the layered inorganic mineral atleast partially modified with an organic ion, it is possible to arrangean adhesion step after adhering the layered inorganic mineral at leastpartially modified with an organic ion, wherein a dispersion liquid ofother fine particles is added and mixed for uniformly adhering fineparticles on a surface of the aggregated particles to form adheredparticles. These adhered particles are formed by heteroaggregation andso on. This adhered-particle dispersion liquid may be heated to atemperature of the glass transition temperature of the resin particlesin the similar manner for fusion to form fused particles.

The fused particles fused in the fusing step exist as acolored-and-fused-particle dispersion liquid in the aqueous medium. In awashing step, the fused particles are taken out from the aqueous medium,and at the same time, impurities and so on mixed in the above steps areremoved. They are then dried, and a toner for developing anelectrostatic image as a powder is obtained.

In the washing step, acidic water, or basic water in some cases, isadded to the fused particles several times in an amount followed bystirring and filtering to obtain a solid content. Pure water is added tothis solid content several times in an amount followed by stirring andfiltering. This operation is repeated several times until a filtrateafter filtration has a pH of about 7, and colored toner particles areobtained. In the drying step, the toner particles obtained in thewashing step is dried at a temperature of less than the glass transitiontemperature. At this time, methods such as circulating dry air andheating under vacuum conditions are taken according to necessity.

A small amount of surfactants may be used in case of the resin-particledispersion liquid not necessarily stable under basic conditions becauseof stability of pH and so on of the colorant dispersion liquid or thereleasing-agent dispersion liquid or for the purpose of obtainingstability over time of the resin-particle dispersion liquid.

Examples of the surfactants include: anionic surfactants of sulfates,sulfonates, phosphate esters, soaps and so on; cationic surfactants ofamine salts, quaternary ammonium salts and so on; and non-ionicsurfactants of polyethylene glycol, alkylphenol ethylene oxide adducts,polyhydric alcohols and so on. Among these, ionic surfactants arepreferable, and the anionic surfactants and cationic surfactants aremore preferable. In the toner of the present invention, the anionicsurfactants generally have high dispersion power and are superior indispersibility of the resin particles and the colorants, and thus thecationic surfactant are advantageous as a surfactant for dispersing thereleasing agent. The non-ionic surfactant is preferably used incombination with the anionic surfactants or the cationic surfactants.These surfactants may be used alone or in combination of two or more.

Specific examples of the anionic surfactant include: fatty acid soapssuch as potassium laurate, sodium oleate, sodium castor oil and so on;sulfuric acid esters such as octyl sulfate, lauryl sulfate, lauryl ethersulfate, nonyl phenyl ether sulfate and so on; lauryl sulfonate,dodecylbenzene sulfonate; sodium alkylnaphthalene sulfonate, naphthalenesulfonate formalin condensate such as trisopropylnaphthalene sulfonate,dibutylnaphthalene sulfonate and so on; sulfonic acid salts such asmonooctyl sulfosuccinate, dioctyl sulfosuccinate, amidosulfonatelaurate, amidosulfonate oleate and so on; phosphoric acid esters such aslauryl phosphate, isopropyl phosphate, nonyl phenyl ether phosphate andso on; dialkylsulfosuccinate salts such as sodium dioctylsulfosuccinateand so on; sulfosuccinate salts such as disodium lauryl sulfosuccinateand so on; and so on.

Specific examples of the cationic surfactant include: amine salts suchas laurylamine hydrochloride, stearylamine hydrochloride, oleylamineacetate, stearylamine acetate, stearylaminopropylamine acetate and soon; quaternary ammonium salts such as lauryltrimethylammonium chloride,dilauryldimethylammonium chloride, distearylammonium chloride,distearyldimethylammonium chloride, lauryldihydroxyethylmethylammoniumchloride, oleyl-bis-polyoxyethylenemethylammonium chloride,lauroylaminopropyldimethylethylammonium ethosulfate,lauroylaminopropyldimethylhydroxyethylammonium perchlorate,alkylbenzenedimethylammonium chloride, alkyltrimethylammonium chlorideand so on.

Specific examples of the non-ionic surfactant include: alkyl ethers suchas polyoxyethylene octyl ether, polyoxyethylene lauryl ether,polyoxyethylene stearyl ether, polyoxyethylene oleyl ether; alkylphenylethers such as polyoxyethylene octylphenyl ether, polyoxyethylenenonylphenyl ether and so on; alkyl esters such as polyoxyethylenelaurate, polyoxyethylene stearate, polyoxyethylene oleate and so on;alkylamines such as polyoxyethylene laurylamine ether, polyoxyethylenestearylamino ether, polyoxyethylene oleylamino ether, polyoxyethylenesoybean amino ether, polyoxyethylene beef tallow amino ether and so on;alkyl amides such as polyoxyethylene lauric amide, polyoxyethylenestearic amide, polyoxyethylene oleic amide and so on; vegetable oilethers such as polyoxyethylene castor oil ether, polyoxyethylene canolaether and so on; alkanolamides such as lauric acid diethanolamide,stearic acid diethanolamide, oleic acid diethanolamide and so on;sorbitan ester ethers such as polyoxyethylene sorbitan monolaurate,polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitanmonostearate, polyoxyethylene sorbitan monooleate and so on.

A content of the surfactant in each dispersion liquid may be about anamount that does not inhibit the characteristics of the presentinvention, and it is generally a small amount. Specifically, for theresin-particle dispersion liquid, it is around 0.01% by mass to 1% bymass, preferably 0.02% by mass to 0.5% by mass, and more preferably 0.1%by mass to 0.2% by mass. When the content is less than 0.01% by mass, apH of the resin-particle dispersion liquid in particular is not in a notsufficiently basic condition, which may cause aggregation. For thecolorant dispersion liquid and the releasing agent dispersion liquid,the content is 0.01% by mass to 10% by mass, preferably 0.1% by mass to5% by mass, and more preferably 0.5% by mass to 0.2% by mass. Thecontent of less than 0.01% by mass is not preferable because ofoccurrence of liberation of specific particles due to differentstability among particles during aggregation. Also, the contentexceeding 10% by mass is not preferable because there are problems ofwidened particle size distribution of particles or difficulty incontrolling the particle diameter.

The toner of the present invention may include, other than the resin,the colorant and the releasing agent, fine particles of other componentssuch as internal additive, charge controlling agent, inorganic granularmaterial, organic granular material, lubricant, polishing agent and soon may be added according to purpose.

The internal additive is used to an extent that does not inhibitcharging property as the toner characteristics. For example, magneticbodies of metals such as ferrite, magnetite, reduced iron, cobalt,manganese, nickel and so on, alloys, or compounds including these metalsare used.

As described above, when the resin-particle dispersion liquid, adispersion liquid of the layered inorganic mineral at least partiallymodified with an organic ion, the colorant dispersion liquid and thereleasing-agent dispersion liquid are mixed, a content of the colorantis 50% by mass or less, and it is preferably 2% by mass to 40% by mass.A content of the layered inorganic mineral at least partially modifiedwith an organic ion is preferably 0.05% by mass to 10% by mass. Also, acontent of the other components is an amount that does not inhibit thepurpose of the present invention. It is generally very small, and it isspecifically 0.01% by mass to 5% by mass, and preferably 0.5% by mass to2% by mass.

In the present invention, as a dispersion medium of the resin-particledispersion liquid, the dispersion liquid of the layered inorganicmineral at least partially modified with an organic ion, the colorantdispersion liquid, the releasing-agent dispersion liquid and thedispersion liquid of other components, aqueous medium is used, forexample. Examples of the aqueous medium include water such as distilledwater, ion-exchanged water and so on, alcohols and so on. These may beused alone or in combination of two or more.

In a step for preparing the aggregated-particle dispersion liquid of thepresent invention, aggregation is caused by adjusting an emulsifyingpower of the emulsifier with its pH, and thereby aggregated particlesare prepared. At the same time, in order to achieve stable and speedyaggregation of the particles and to obtain the aggregated particleshaving a narrower particle size distribution, an aggregating agent maybe added. As the aggregating agent, a compound having a charge or one ormore valences is preferable, and specific examples thereof include:water-soluble surfactants such as ionic surfactant, nonionic surfactantabove and so on; acids such as hydrochloric acid, sulfuric acid, nitricacid, acetic acid, oxalic acid and so on; metal salts of inorganic acidssuch as magnesium chloride, sodium chloride, aluminum sulfate, calciumsulfate, ammonium sulfate, aluminum nitrate, silver nitrate, coppersulfate, sodium carbonate and so on; metal salts of aliphatic acids oraromatic acids such as sodium acetate, potassium formate, sodiumoxalate, sodium phthalate, potassium salicylate and so on; metal saltsof phenols such as sodium phenolate and so on; inorganic acid salts ofaliphatic or aromatic amines such as metal salts of amino acids,triethanolamine hydrochloride, aniline hydrochloride and so on. Themetal salts of inorganic acids are preferable in terms of performanceand usage when stability of the aggregated particles, stability of theaggregating agent against heat and time, and removal of the aggregatingagent during washing are considered.

An added amount of these aggregating agents varies depending on thenumber of valences of the charge, but it is nonetheless small. It isaround 3% by mass or less for a monovalent agent, it is around 1% bymass or less for a divalent agent, and it is around 0.5% by mass or lessfor a trivalent agent. The added amount of the aggregating agent ispreferably small, and compounds having larger valences are preferablesince it may reduce the added amount.

<Dissolution-Suspension Method>

In a toner manufacturing method of the present invention, a binder resinor a toner material having binder resin materials and a colorant as maincomponents is dissolved or dispersed in an organic solvent, thus formedsolution or dispersion liquid is emulsified or dispersed in an aqueousmedium to prepare an emulsified liquid or a dispersion liquid, and adesired toner is manufactured. Preferably, a solution or a dispersionliquid of toner materials including at least a compound having an activehydrogen group and a binder resin precursor having a site capable ofreacting with the compound having an active hydrogen group is emulsifiedor dispersed in an aqueous medium, the compound having an activehydrogen group and the binder resin precursor having a site capable ofreacting with the compound having an active hydrogen group are reactedin the aqueous medium to form toner base particles including at least anadhesive base, and thereby a desired toner is manufactured.

—Solution or Dispersion Liquid of Toner Materials—

The solution or dispersion liquid of toner materials is prepared bydissolving or dispersing toner materials in a solvent. The tonermaterials are not particularly restricted as long as it is able to forma toner, and it may be appropriately selected according to purpose. Forexample, it includes either the compound having an active hydrogen groupor the binder resin precursor having a site capable of reacting with thecompound having an active hydrogen group (prepolymer), and it mayfurther include the other components such as non-modified polyesterresin, releasing agent, colorant, charge controlling agent and so onaccording to necessity. The solution or dispersion liquid of tonermaterials is preferably prepared by dissolving or dispersing the tonermaterials in an organic solvent. Here, the organic solvent is preferablyremoved after during granulation or after granulation of the toner.

—Organic Solvent—

The organic solvent for dissolving or dispersing the toner materials isnot particularly restricted as long as it is a solvent which maydissolve or disperse the toner materials, and it may be appropriatelyselected according to purpose. Nonetheless, those having a boiling pointof less than 150° C. are preferable in view of easy removal duringgranulation or after granulation of the toner. Examples thereof includetoluene, xylene, benzene, carbon tetrachloride, methylene chloride,1,2-dichloroethane, 1,1,2-trichloroethane, trichlorethylene, chloroform,monochlorobenzene, dichloroethylidene, methyl acetate, ethyl acetate,methyl ethyl ketone, methyl isobutyl ketone and so on. Also, anester-based solvent is preferable, and ethyl acetate is particularlypreferable. These may be used alone or in combination of two or more. Anamount of the organic solvent used is not particularly restricted, andit may be appropriately selected according to purpose. Nonetheless, itis preferably 40 parts by mass to 300 parts by mass, more preferably 60parts by mass to 140 parts by mass, and further preferably 80 parts bymass to 120 parts by mass with respect to 100 parts by mass of the tonermaterials. Here, the solution or dispersion liquid of the tonermaterials is prepared by dissolving or dispersing the toner materialssuch as compound having an active hydrogen group, binder resin precursorhaving a site capable of reacting with a compound having an activehydrogen group, non-modified polyester resin, releasing agent, colorant,charge controlling agent, and so on in the organic solvent. Also, amongthe toner materials, components other than the binder resin precursorhaving a site capable of reacting with the compound having an activehydrogen group (prepolymer) may be added and mixed in the aqueous mediumin a preparation of the aqueous medium described hereinafter or may beadded to the aqueous medium along with the solution or dispersion liquidwhen the solution or dispersion liquid of toner materials is added tothe aqueous medium.

—Aqueous Medium—

The aqueous medium is not particularly restricted, and it may beappropriately selected from heretofore known ones. For example, water, asolvent miscible with water, a mixture thereof and so on may be used.Among these, water is particularly preferable. A solvent miscible withwater is not particularly restricted as long as it is miscible withwater. Examples thereof include alcohols, dimethylformamide,tetrahydrofuran, cellosolves, lower ketones and so on. Examples of thealcohols include methanol, isopropanol, ethylene glycol and so on. Also,examples of the lower ketones include acetone, methyl ethyl ketone andso on. These may be used alone or in combination of two or more.

<<Emulsification or Dispersion>>

Emulsification or dispersion of the solution or the dispersion liquid ofthe toner materials in the aqueous medium is preferably carried out bydispersing the solution or the dispersion liquid of the toner materialsin the aqueous medium with stirring. A dispersing method is notparticularly restricted, and it may be appropriately selected accordingto purpose. For example, it may be carried out using heretofore knowndispersion equipment. Examples of the dispersion equipment include alow-speed shearing equipment, a high-speed shearing equipment and so on.In this toner manufacturing method, in the emulsification or dispersion,by subjecting the compound having an active hydrogen group and thebinder resin precursor having a site capable of reacting with thecompound having an active hydrogen group to an elongation reaction orcrosslinking reaction, the adhesive base is formed.

—Adhesive Base—

The adhesive base exhibits adhesive property to recording media such aspaper, and it preferably includes an adhesive polymer formed by reactingthe compound having an active hydrogen group and the binder resinprecursor having a site capable of reacting with the compound having anactive hydrogen group in an aqueous medium. Here, it may include abinder resin appropriately selected from heretofore known binder resins.A weight-average molecular weight of the adhesive base is notparticularly restricted, and it may be appropriately selected accordingto purpose. Nonetheless, it is preferably 3,000 or greater, morepreferably 5,000 to 1,000,000, and particularly preferably 7,000 to500,000. When the weight-average molecular weight is less than 3,000,hot-offset resistance may degrade.

A glass transition temperature (Tg) of the adhesive base is notparticularly restricted, and it may be appropriately selected accordingto purpose. For example, it is preferably 30° C. to 70° C., and morepreferably 40° C. to 65° C. When the glass transition temperature (Tg)is less than 30° C., heat-resistant storage stability of the toner maydegrade. When it exceeds 70° C., low-temperature fixing property may beinsufficient. The electrophotographic toner of this embodiment exhibitsfavorable storage stability despite a low glass transition temperaturecompared to a conventional polyester toner because of coexistingpolyester resins formed by crosslinking reaction or elongation reaction.

The glass transition temperature (Tg) may be measured according to thefollowing method using, for example, a TG-DSC system TAS-100(manufactured by Rigaku Corporation). First, about 10 mg of a toner isplaced in a sample container made of aluminum, and the sample containeris mounted on a holder unit and set in an electric furnace. It is heatedfrom a room temperature to 150° C. at a heating rate of 10° C./min andthen allowed to stand at 150° C. for 10 minutes. Then, the sample iscooled to a room temperature and allowed to stand for 10 minutes.Thereafter, under a nitrogen atmosphere, it is heated to 150° C. at aheating rate of 10° C./min and a DSC curve is measured by a differentialscanning calorimeter (DSC). From the obtained DSC curve, using ananalysis system of the TG-DSC system TAS-100 system, the glasstransition temperature (Tg) is calculated from a contact point of atangent of an endothermic curve near the glass transition temperature(Tg) and a baseline.

The resin for the adhesive base is not particularly restricted, and itmay be appropriately selected according to purpose. Nonetheless, apolyester resin is particularly preferable. The polyester resin is notparticularly restricted and may be appropriately selected according topurpose. Nonetheless, a urea-modified polyester resin is particularlyfavorable, for example. The urea-modified polyester resin is obtained byreacting amines (B) as a compound having an active hydrogen group and anisocyanate group-containing polyester prepolymer (A) as the binder resinprecursor having a site capable of reacting with the compound having anactive hydrogen group in an aqueous medium. The urea-modified polyesterresin may include a urethane bond other than a urea bond. In this case,a molar ratio between the urea bond and the urethane bond (ureabond/urethane bond) is not particularly restricted, and it may beappropriately selected according to purpose. Nonetheless, it ispreferably 100/0 to 10/90, more preferably 80/20 to 20/80, andparticularly preferably 60/40 to 30/70. When the above molar ratio isless than 10/90, hot-offset resistance may degrade.

Specific examples of the favorable urea-modified polyester resin includethe following.

(1) A mixture of: a polyester prepolymer obtained by reacting apolycondensate of 2-mole ethylene-oxide adduct of bisphenol A andisophthalic acid with isophorone diisocyanate, which is urea-modifiedwith isophoronediamine; and a polycondensate of 2-mole ethylene-oxideadduct of bisphenol A and isophthalic acid(2) A mixture of: a polyester prepolymer obtained by reacting apolycondensate of 2-mole ethylene-oxide adduct of bisphenol A andisophthalic acid with isophorone diisocyanate, which is urea-modifiedwith isophoronediamine; and a polycondensate of 2-mole ethylene-oxideadduct of bisphenol A and terephthalic acid(3) A mixture of: a polyester prepolymer obtained by reacting apolycondensate of 2-mole ethylene-oxide adduct of bisphenol A/2-molepropylene-oxide adduct of bisphenol A and terephthalic acid withisophorone diisocyanate, which is urea-modified with isophoronediamine;a polycondensate of 2-mole ethylene-oxide adduct of bisphenol A/2-molepropylene-oxide adduct of bisphenol A and terephthalic acid(4) A mixture of: a polyester prepolymer obtained by reacting apolycondensate of 2-mole ethylene-oxide adduct of bisphenol A/2-molepropylene-oxide adduct of bisphenol A and terephthalic acid withisophorone diisocyanate, which is urea-modified with isophoronediamine;a polycondensate of 2-mole propylene-oxide adduct of bisphenol A andterephthalic acid(5) A mixture of: a polyester prepolymer obtained by reacting apolycondensate of 2-mole ethylene-oxide adduct of bisphenol A andterephthalic acid with isophorone diisocyanate, which is modified withhexamethylene diamine; and a polycondensate of 2-mole ethylene-oxideadduct of bisphenol A and terephthalic acid(6) A mixture of: a polyester prepolymer obtained by reacting apolycondensate of 2-mole ethylene-oxide adduct of bisphenol A andterephthalic acid with isophorone diisocyanate, which is modified withhexamethylene diamine; and a polycondensate of 2-mole ethylene-oxideadduct of bisphenol A/2-mole propylene-oxide adduct of bisphenol A andterephthalic acid(7) A mixture of: a polyester prepolymer obtained by reacting apolycondensate of 2-mole ethylene-oxide adduct of bisphenol A andterephthalic acid with isophorone diisocyanate, which is urea-modifiedwith ethylene diamine; and a polycondensate of 2-mole ethylene-oxideadduct of bisphenol A and terephthalic acid(8) A mixture of: a polyester prepolymer obtained by reacting apolycondensate of 2-mole ethylene-oxide adduct of bisphenol A andisophthalic acid with diphenylmethane diisocyanate, which isurea-modified with hexamethylene diamine; and a polycondensate of 2-moleethylene-oxide adduct of bisphenol A and isophthalic acid(9) A mixture of: a polyester prepolymer obtained by reacting apolycondensate of 2-mole ethylene-oxide adduct of bisphenol A/2-molepropylene-oxide adduct of bisphenol A and terephthalicacid/dodecenylsuccinic anhydride with diphenylmethane diisocyanate,which is urea-modified with hexamethylene diamine; and a polycondensateof 2-mole ethylene-oxide adduct of bisphenol A/2-mole propylene-oxideadduct of bisphenol A and terephthalic acid(10) A mixture of: a polyester prepolymer obtained by reacting apolycondensate of 2-mole ethylene-oxide adduct of bisphenol A andisophthalic acid with toluene diisocyanate, which is urea-modified withhexamethylene diamine; and a polycondensate of 2-mole ethylene-oxideadduct of bisphenol A and isophthalic acid

The adhesive base (for example, a urea-modified polyester resin) may beformed by, for example, (1) emulsifying or dispersing a solution or adispersion liquid of toner materials including the binder resinprecursor having a site capable of reacting with the compound having anactive hydrogen group (for example, isocyanate group-containingpolyester prepolymer (A)) in the aqueous medium with the compound havingan active hydrogen group (for example, amines (B)) to form oil dropletsand subjecting them to an elongation reaction or a crosslinking reactionin the aqueous medium, or (2) emulsifying or dispersing the solution ordispersion liquid of toner materials in aqueous medium in which thecompound having an active hydrogen group is added beforehand to form oildroplets and subjecting them to an elongation reaction or a crosslinkingreaction in the aqueous medium. Alternatively, it may be produced by (3)adding and mixing the solution or dispersion liquid of toner materialsin the aqueous medium followed by adding the compound having an activehydrogen group to form oil droplets and subjecting them to an elongationreaction or a crosslinking reaction in the aqueous medium from particleinterfaces. Here, in case of (3), the modified polyester resin ispredominantly formed on a surface of the toner being formed, and aconcentration gradient may be allocated on the toner particles.

Reaction conditions for forming the adhesive base by emulsification ordispersion are not particularly restricted, and they may beappropriately selected depending on a combination of the binder resinprecursor having a site capable of reacting with the compound having anactive hydrogen group and the compound having an active hydrogen group.Here, a reaction time is preferably 10 minutes to 40 hours, and morepreferably 2 hours to 24 hours.

As a method for stably forming a dispersion body including the binderresin precursor having a site capable of reacting with the compoundhaving an active hydrogen group (for example, isocyanategroup-containing polyester prepolymer (A)) in the aqueous medium, forexample, the solution or dispersion liquid of toner materials preparedby dissolving or dispersing the toner materials such as binder resinprecursor having a site capable of reacting with the compound having anactive hydrogen group (for example, isocyanate group-containingpolyester prepolymer (A)), the colorant, the releasing agent, the chargecontrolling agent, the non-modified polyester resin and so on in anorganic solvent is added in the aqueous medium, and it is dispersed by ashearing force.

An amount of the aqueous medium used in the emulsification or dispersionis preferably 50 parts by mass to 2,000 parts by mass, and morepreferably 100 parts by mass to 1,000 parts by mass with respect to 100parts by mass of the toner materials. When the amount used is less than50 parts by mass, the toner materials are poorly dispersed, and thereare cases where toner particles having a predetermined particle diametercannot be obtained. When it exceeds 2,000 parts by mass, a productioncost increases.

In the emulsification or dispersion, a dispersant is preferably usedaccording to necessity for stabilizing the oil droplets and forsharpening the particle size distribution while obtaining a desiredshape. The dispersant is not particularly restricted, and it may beappropriately selected according to purpose. Examples thereof includesurfactants, hardly water-soluble inorganic compound dispersants,polymeric protective colloid and so on. These may be used alone or incombination of two or more. Among these, the surfactants are preferable.

Examples of the polymeric protective colloid include acids,(meth)acrylic monomers containing a hydroxyl group, vinyl alcohol orethers of vinyl alcohol, esters of vinyl alcohol and a compoundcontaining a carboxyl group, amide compounds and methylol compoundsthereof, chlorides, homopolymers or copolymers of units containing anitrogen atom or a heterocycle thereof, polyoxyethylenes, celluloses andso on. Examples of the acids include acrylic acid, methacrylic acid,α-cyanoacrylic acid, β-cyanomethacrylic acid, itaconic acid, crotonicacid, fumaric acid, maleic acid, maleic anhydride and so on. Examples ofthe (meth)acrylic monomer containing a hydroxyl group includeβ-hydroxyethyl acrylate, β-hydroxyethyl methacrylate, β-hydroxypropylacrylate, β-hydroxypropyl methacrylate, γ-hydroxypropyl acrylate,γ-hydroxypropyl methacrylate, 3-chloro-2-hydroxypropyl acrylate,3-chloro-2-hydroxypropyl methacrylate, diethylene glycol monoacrylate,diethylene glycol monomethacrylate, glycerin monoacrylate, glycerinmonomethacrylate, n-methylol acrylamide, n-methylol methacrylamide andso on.

Examples of the vinyl alcohol or ethers of vinyl alcohol include vinylmethyl ether, vinyl ethyl ether, vinyl propyl ether and so on. Also,examples of the esters of vinyl alcohol and a compound containing acarboxyl group include vinyl acetate, vinyl propionate, vinyl butyrateand so on. Also, examples of the amide compounds and the methylolcompounds thereof include acrylamide, methacrylamide, diacetoneacrylamide acid, and methylol compounds thereof.

Examples of the chlorides include acrylic acid chloride, methacrylicacid chloride and so on. Also, homopolymers or copolymers of unitscontaining a nitrogen atom or a heterocycle thereof include vinylpyridine, vinyl pyrrolidone, vinyl imidazole, ethylene imine and so on.

Examples of the polyoxyethylenes include polyoxyethylene,polyoxypropylene, polyoxyethylene alkyl amine, polyoxypropylene alkylamine, polyoxyethylene alkyl amides, polyoxypropylene alkyl amides,polyoxyethylene nonylphenyl ether, polyoxyethylene laurylphenyl ether,polyoxyethylene stearylphenyl ester, polyoxyethylene nonylphenyl esterand so on. Also, examples of the celluloses include methyl cellulose,hydroxyethyl cellulose, hydroxypropyl cellulose and so on.

When a dispersion stabilizer which may be dissolved in an acid or analkali such as calcium phosphate salts and so on, it is possible toremove the calcium phosphate salts from the fine particles by, forexample, dissolving the calcium phosphate salts by an acid such ashydrochloric acid and so on followed by washing with water or bydecomposing with an enzyme.

—Anionic Surfactant—

Examples of the anionic surfactants used in the manufacturing method ofthe present invention include alkylbenzene sulfonate, α-olefinsulfonate, phosphate esters and so on, and anionic surfactantscontaining a fluoroalkyl group are favorable. Examples of the anionicsurfactants containing a fluoroalkyl group include afluoroalkylcarboxylic acid (C2 to C10) or metal salts thereof, disodiumperfluorooctane sulfonyl glutamate, sodium 3-[ω-fluoroalkyl (C6 to C11)oxy]-1-alkyl (C3 to C4)sulfonate, sodium 3-[ω-fluoroalkanoyl (C6 toC8)-N-ethylamino]-1-propane sulfonate, fluoroalkyl (C11 to C20)carboxylic acid or metal salts thereof, perfluoroalkylcarboxylic acid(C7 to C13) or metal salts thereof, perfluoroalkyl (C4 to C12) sulfonicacid or metal salts thereof, perfluorooctane sulfonic aciddiethanolamide, N-propyl-N-(2-hydroxyethyl)perfluorooctane sulfonamide,perfluoroalkyl (C6 to C10) sulfonamide propyl trimethyl ammonium salt,perfluoroalkyl (C6 to C10)-N-ethyl sulfonyl glycine salts,monoperfluoroalkyl (C6 to C16) ethyl phosphate esters and so on.

Examples of commercial products of anionic surfactants having afluoroalkyl group include: SURFLON S-111, S-112, S-113 (manufactured byAsahi Glass Co., Ltd.); FLUORAD FC-93, FC-95, FC-98, FC-129(manufactured by Sumitomo 3M Ltd.); UNIDYNE DS-101, DS-102 (manufacturedby Daikin Industries, Ltd.); MEGAFACE F-110, F-120, F-113, F-191, F-812,F-833 (manufactured by DIC Corporation); EFTOP EF-102, 103, 104, 105,112, 123A, 123B, 306A, 501, 201, 204 (manufactured by Tochem ProductsInc.); FTERGENT F-100, F150 (manufactured by Neos Company Ltd.), and soon.

<<Removal of Organic Solvent>>

The organic solvent is removed from emulsified slurry obtained byemulsification or dispersion. Exemplary methods for removing the organicsolvent include: (1) gradually heating the whole reaction system tocompletely evaporate and remove the organic solvent in the oil droplets;(2) spraying the emulsified dispersion in a dry atmosphere to completelyremove the non-water-soluble organic solvent in the oil droplets and toform toner particles and additionally evaporating and removing theaqueous dispersant, and so on. Once the organic solvent is removed,toner particles are formed. The toner particles thus formed aresubjected to washing, drying and so on, further followed byclassification and so on, if desired. The classification is carried outby removing a fine-particle portion in a liquid by a cyclone, adecanter, a centrifuge and so on. Here, classification operation may becarried out on a powder obtained after drying.

(Image Forming Apparatus and Image Forming Method)

An image forming apparatus of the present invention includes: anelectrostatic latent image bearing member; an electrostatic latent imageforming unit (a charger and an exposure device); a developing unit; atransfer unit; a fixing unit; and a cleaning unit, and it may furtherinclude other units such as neutralizing unit, recycling unit,controlling unit and so on according to necessity.

An image forming method of the present invention includes: anelectrostatic latent image forming step (charging and exposure); adeveloping step; a transfer step; a fixing step; and a cleaning step,and it may further include other steps such as neutralizing step,recycling step, controlling step and so on according to necessity.

<Electrostatic Latent Image Bearing Member>

A material, shape, structure, size and so on of the electrostatic imagebearing member (hereinafter, it may also be referred to as an “imagebearing member” or a “photoconductor”) may be appropriately selectedfrom heretofore known ones. Examples of the material include: inorganicmaterials such as amorphous silicon, selenium and so on; and organicmaterials such as polysilane, phthalopolymethine and so on, and theamorphous silicon for its long service life. Also, the shape ispreferably a drum.

<Electrostatic Latent Image Forming Unit and Electrostatic Latent ImageForming Step>

The electrostatic latent image forming unit is a unit for forming anelectrostatic latent image on the electrostatic image bearing member.The electrostatic latent image forming step is a step for forming anelectrostatic latent image on the electrostatic image bearing member.The electrostatic latent image forming step may be favorably carried outby the electrostatic latent image forming unit.

The electrostatic latent image may be formed by uniformly charging asurface of the image bearing member followed by an image-wise exposure,and it may be carried out by the electrostatic latent image formingunit. The electrostatic latent image forming unit preferably includes acharger (charging unit) which uniformly charges the surface of the imagebearing member, and an exposure device (exposure unit) which exposes thesurface of the image bearing member.

The charging may be carried out by applying a voltage on the surface ofthe image bearing member using the charger. The charger may beappropriately selected according to purpose. Nonetheless, heretoforeknown contact charger, non-contact charger which makes use of coronadischarge such as corotron, scorotron and so on, and so on equipped withan electrically conductive or semiconductive roller, brush, film, rubberblade and so on may be exemplified.

The exposure may be carried out by exposing the surface of the imagebearing member using the exposure device. The exposure device may beappropriately selected according to purpose. Nonetheless, variousexposure devices such as duplication optical system, rod lens arraysystem, laser optical system, liquid crystal shutter optical system andso on may be used. Here, a back-light system which carries out anexposure from a back surface of the image bearing member may beemployed.

<Developing Unit and Developing Step>

The developing unit is a developing unit which is equipped with thetoner of the present invention and forms a visible image by developingthe electrostatic latent image with the toner. The developing step is astep for forming a visible image by developing an electrostatic latentimage with the toner of the present invention. The developing step maybe favorably carried out by the developing unit.

The visible image may be formed using the developing unit. Thedeveloping unit may be appropriately selected from heretofore knownones, and it favorably includes a developing device which contains thetoner of the present invention and may impart the toner to theelectrostatic latent image in a contact or non-contact manner. Thedeveloping device may be of a dry development method or a wetdevelopment method. Also, it may be of a single-color developing deviceor a multi-color developing device. Specific examples thereof include adeveloping device including a stirrer which charges the developer byfrictional stirring and a rotatable magnet roller and so on. A developercontained in the developing device is a developer which uses the tonerof the present invention, and it may be a one-component developer or atwo-component developer.

In the developing device including the two-component developer, thetoner and a carrier are mixed and stirred, and the toner is charged bythe friction generated at that time. The toner is held in a state of earstanding on a surface of the rotating magnet roller, and a magneticbrush is formed. Since the magnet roller is arranged in a vicinity ofthe image bearing member, a part of the toner which constitutes themagnetic brush formed on the surface of the magnet roller is transferredto the surface of the image bearing member by an electrical attractionforce. As a result, the electrostatic latent image is developed by thetoner, and a visible image is formed by the toner on the surface of theimage bearing member.

<Transfer Unit and Transfer Step>

The transfer unit is a unit for transferring the visible image on theelectrostatic latent image bearing member to a recording medium. Thetransfer step is a step for transferring the visible image on theelectrostatic latent image bearing member to a recording medium. Thetransfer step may be favorably carried out by the transfer unit.

The transfer step preferably includes a primary transfer of the visibleimage to an intermediate transfer member using an intermediate transfermember and a secondary transfer of the visible image to the recordingmedium. At this time, as the toner to be used, a monochrome, afull-color or a transparent toner may be used. Usually, two or morecolors are simultaneously interposed and developed, and thus it morepreferably includes a primary transfer step which forms a compositetransfer image by transferring the visible image on an intermediatetransfer member and a secondary transfer step which transfers thecomposite transfer image on a recording medium.

The transfer may be carried out by charging the image bearing memberusing the transfer unit. The transfer unit preferably includes a primarytransfer unit which transfers the visible image on the intermediatetransfer member to form the composite transfer image and a secondarytransfer unit which transfers the composite transfer image to therecording medium. Here, the intermediate transfer member may beappropriately selected from heretofore known transfer bodies accordingto purpose, and a transfer belt and so on may be used.

The transfer unit preferably includes a transfer device which peels offand charges the visible image formed on the image bearing member to aside of the recording medium. The transfer unit may be one, or two ormore. Specific examples of the transfer device include a corona transferdevice by corona discharge, a transfer belt, a transfer roller, apressure transfer roller, an adhesive transfer device and so on. Here,the recording medium may be appropriately selected from heretofore knownrecording media, and recording paper and so on may be used.

<Fixing Unit and Fixing Step>

The fixing unit is a unit for fixing a transfer image transferred on therecording medium. The fixing step is a step for fixing the transferimage transferred on the recording medium. The fixing step may bepreferably carried out by the fixing unit.

The fixing step is a step for fixing the visible image transferred onthe recording medium using the fixing unit. The fixing may be carriedout every time a toner of one color is transferred on the recordingmedium, or it may be carried out once when the toners of respectivecolors are laminated. The fixing unit may be appropriately selectedaccording to purpose. Nonetheless, a heretofore known heating andpressurizing unit may be used. Examples of the heating and pressurizingunit include a combination of a heat roller and a pressure roller, acombination of a heat roller, a pressure roller and an endless belt andso on. Heating in the heating and pressurizing unit is preferablycarried out at 80° C. to 200° C. Here, a heretofore known optical fixingdevice may be used according to purpose with or in place of the fixingstep and the fixing unit, for example.

<Cleaning Unit and Cleaning Step>

The cleaning unit is a unit for removing a toner remaining on the imagebearing member. The cleaning step is a step for removing a tonerremaining on the image bearing member. The cleaning step may befavorably carried out by the cleaning unit.

The cleaning unit may be appropriately selected from heretofore knowncleaners, and a magnetic brush cleaner, an electrostatic brush cleaner,a magnetic roller cleaner, a blade cleaner, a brush cleaner, a webcleaner and so on may be used. It is preferable to use the bladecleaner.

The neutralizing step is a step for neutralizing the image bearingmember by applying a neutralizing bias, and it may be carried out usinga neutralizing unit.

The neutralizing unit may be appropriately selected from heretoforeknown neutralizing devices, and a neutralizing lamp and so on may beused.

The controlling step is a step for controlling the above steps, and itmay be carried out using a controlling unit. The controlling unit may beappropriately selected according to purpose, and devices such assequencer, computer and so on may be used.

A process cartridge of the present invention is used for the imageforming apparatus of the present invention. It integrally support animage bearing member, and at least one unit selected from the chargingunit, the developing unit and the cleaning unit, and it is detachablyattached to the image forming apparatus main body of the presentinvention.

FIG. 1 illustrates one example of an image forming apparatus used in thepresent invention. An image forming apparatus 100A is equipped with: adrum-shaped photoconductor 10 as an image bearing member; a chargingroller 20 as a charging unit, an exposure apparatus 30 as an exposureunit, a developing apparatus 40 as a developing unit, an intermediatetransfer member 50, a cleaning apparatus 60 as a cleaning unit, and aneutralizing lamp 70 as a neutralizing unit.

The intermediate transfer member 50 is an endless belt, stretched bythree (3) rollers 51 so that it can move in a direction of the arrow. Apart of the three (3) rollers 51 also functions as a transfer biasroller which may apply a predetermined transfer bias (primary transferbias) on the intermediate transfer member 50. In a vicinity of theintermediate transfer member 50, a cleaning apparatus 90 including acleaning blade is arranged. Also, a transfer roller 80 which can apply atransfer bias for transferring (secondary transfer) the visible image(toner image) on recording paper 95 as a recording medium is disposedfacing the intermediate transfer member. In a periphery of theintermediate transfer member 50, a corona charger 58 for applying acharge to the toner image on the intermediate transfer member 50 isdisposed between a contact portion of the photoconductor 10 with theintermediate transfer member 50 and a contact portion of theintermediate transfer member 50 with the transfer paper 95 in adirection of rotation of the intermediate transfer member 50.

The developing apparatus 40 is configured with: a developing belt 41 asa developer bearing member; and a black developing device 45K, a yellowdeveloping device 45Y, a magenta developing device 45M and a cyandeveloping device 45C disposed around the developing belt 41. Here, theblack developing device 45K is equipped with a developer container 42K,a developer supply roller 43K and a developing roller 44K; the yellowdeveloping device 45Y is equipped with a developer container 42Y, adeveloper supply roller 43Y and a developing roller 44Y; the magentadeveloping device 45M is equipped with a developer container 42M, adeveloper supply roller 43M and a developing roller 44M, a cyandeveloping device 45C is equipped with a developer container 42C, adeveloper supply roller 43C and a developing roller 44C. Also, thedeveloping belt 41 is an endless belt, stretched by a plurality of beltrollers so that it moves in a direction of the arrow, and a part thereofis in contact with the photoconductor 10.

In the image forming apparatus 100A, the photoconductor 10 is uniformlycharged by the charging roller 20, then the photoconductor 10 is exposedusing the exposure apparatus 30, and the electrostatic latent image isformed. Next, the electrostatic latent image formed on thephotoconductor 10 is developed by supplying a developer from thedeveloping apparatus 40, and a toner image is formed. Further, the tonerimage is transferred (primary transfer) on the intermediate transfermember 50 by the voltage applied by the roller 51, and then transferred(secondary transfer) on the recording paper 95. As a result, a transferimage is formed on the recording paper 95. Here, a toner remaining onthe photoconductor 10 is removed by the cleaning apparatus 60 includingthe cleaning blade, and the charge of the photoconductor 10 isneutralized by the neutralizing lamp 70.

FIG. 2 illustrates another example of an image forming apparatus used inthe present invention. An image forming apparatus 100B has the sameconfiguration and the same effect as the image forming apparatus 100Aexcept that the developing belt 41 is not provided and that, around thephotoconductor drum 10, the black developing unit 45K, the yellowdeveloping unit 45Y, the magenta developing unit 45M and the cyandeveloping unit 45C are disposed to face directly to the photoconductordrum 10. Here, in FIG. 2, elements equivalent to those in FIG. 1 areidentified by the same signs.

FIG. 3 illustrates another example of an image forming apparatus used inthe present invention. An image forming apparatus 100C is a tandem colorimage forming apparatus. The image forming apparatus 100C is equippedwith a copying apparatus main body 150, a paper feed table 200, ascanner 300, and an automatic document feeder 400. In the copyingapparatus main body 150, an intermediate transfer member 50 as anendless belt is provided at a central portion thereof. Also, theintermediate transfer member 50 is stretched by support roller 14, 15and 16 so that it may move in a clockwise direction in the figure. In avicinity of the support roller 15, an intermediate transfer membercleaning apparatus 17 is disposed to remove a toner remaining on theintermediate transfer member 50. A tandem developing device 120 thatfour (4) colors image forming units 18 of yellow, cyan, magenta andblack are arranged in parallel is disposed facing the intermediatetransfer member 50 stretched by the support rollers 14 and 15 in aconveying direction thereof. In a vicinity of the tandem developingdevice 120, an exposure apparatus 21 is disposed. A secondary transferapparatus 22 is disposed on a side of the intermediate transfer member50 opposite to the side of the tandem developing device 120. In thesecondary transfer apparatus 22, a secondary transfer belt 24 as anendless belt is stretched by a pair of rollers 23, and recording paperconveyed on the secondary transfer belt 24 and the intermediate transfermember 50 may contact with each other. A fixing apparatus 25 is disposedin a vicinity of the secondary transfer apparatus 22. The fixingapparatus 25 is equipped with a fixing belt 26 as an endless belt and apressure roller 27 pressed by the fixing belt 26.

Here, in the image forming apparatus 100C, a sheet inverting apparatus28 is disposed in a vicinity of the secondary transfer apparatus 22 andthe fixing apparatus 25 for inverting the transfer paper. Thereby,images may be formed on both sides of recording paper.

Next, formation of a full-color image using the tandem developing device120 (color copy) is explained. First, a document is set on a documenttable 130 of the automatic document feeder 400. Alternatively, theautomatic document feeder 400 is opened, the document is set on acontact glass 32 of the scanner 300, and the automatic document feeder400 is closed.

The scanner 300 activates after the document is conveyed and transferredto the contact glass 32 in the case the document has been set on theautomatic document feeder 400, or right away in the case the documenthas been set on the contact glass 32, and a first traveling body 33 anda second travelling body 34 travel. At this time, a light is irradiatedfrom the first traveling body 33 and is reflected by a surface of thedocument. The reflected light is reflected by a mirror of the secondtravelling body 34 and received by a reading sensor 36 through animaging lens 35. Thereby, the color document (color image) is read, andimage information of respective colors, namely black, yellow, magentaand cyan, are obtained. The image information of the respective colorsare transmitted to the image forming unit 18 of the respective colors inthe tandem developing device 120, and toner images of the respectivecolors are formed.

The toner image on the black photoconductor 10K, the toner image on theyellow photoconductor 10Y, the toner image on the magenta photoconductor10M and the toner image on the cyan photoconductor 10C are sequentiallytransferred (primary transfer) on the intermediate transfer member 50.Then, the toner images of the respective colors are superimposed on theintermediate transfer member 50, and a composite color image (colortransfer image) is formed.

As illustrated in FIG. 4, each of the image forming unit 18 of therespective colors in the tandem developing device 120 includes: aphotoconductor 10; a charger 59 which uniformly charges thephotoconductor 10; an exposure apparatus 21 which exposes (L, in thefigure) the photoconductor 10 based on the image information of therespective colors to form an electrostatic latent image on thephotoconductor 10; a developing device 61 which develops theelectrostatic latent image using a toner of the respective color to forma toner image of the respective color on the photoconductor 10; atransfer charger 62 which transfers the toner image of the respectivecolor on the intermediate transfer member 50; a photoconductor cleaningapparatus 63; and a neutralizing device 64.

Meanwhile, in the paper feed table 200, one of paper-feed rollers 142 ais selectively rotated to feed recording paper from one of papercassettes 144 equipped in multiple stages in a paper bank 143. Therecording paper is separated one by one by a separation roller 145 a andsent to a feed path 146. Each recording paper is conveyed by a conveyingroller 147 and guided to a feed path 148 of the copier main body, and itis stopped by striking a registration roller 49. Alternatively, apaper-feed roller 142 b is rotated to feed recording paper on a manualfeed tray 52. The recording paper is separated one by one by aseparation roller 145 b and guided to a manual feed path 53, and it isstopped similarly by striking the registration roller 49. Here, theregistration roller 49 is generally used while grounded, but it may beused in a state that a bias is applied for removing paper dust on thesheet.

Next, by rotating the registration roller 49 in accordance with thetiming of the color transfer image formed on the intermediate transfermember 50, the recording paper is fed between the intermediate transfermember 50 and the secondary transfer apparatus 22. Thereby, the colortransfer image is formed on the recording paper. Here, the tonerremaining on the intermediate transfer belt 50 after transfer is cleanedby the intermediate transfer member cleaning apparatus 17.

The recording paper on which the color transfer image is formed isconveyed to the fixing apparatus 25 by the secondary transfer apparatus22, and the color transfer image is fixed on the recording paper by heatand pressure. Thereafter, the recording paper is switched by a switchingclaw 55, and it is discharged by a discharge roller 56 and stacked on adischarge tray 57. Alternatively, the recording paper is switched by theswitching claw 55, inverted by a sheet inverting apparatus 28 and guidedagain to the transfer position. An image is formed on a rear surface aswell, and then it is discharged by the discharge roller 56 and stackedon the discharge tray 57.

A process cartridge related to the present invention is used in theimage forming apparatus of the present invention. It integrally supportsan image bearing member and at least any one apparatus selected from acharging apparatus, a developing apparatus, and a cleaning apparatus,and it is detachably attached to the image forming apparatus main body.

EXAMPLES

Hereinafter, the present invention is further explained in detail withexamples and comparative examples. Here, the present invention is notlimited to the described examples and comparative example. “Part” and“%” in the example denote “parts by mass” and “% by mass”, respectively,unless otherwise specified.

[Production of Toner]

Specific preparation examples of toners used for evaluation areexplained. The toner used in the present invention is not limited tothese examples.

Example 1 <Toner Base Particles A> —Synthesis of Crystalline PolyesterResin—

A 5-L four-necked flask equipped with a nitrogen inlet tube, adehydration tube, a stirrer and a thermocouple was charged with 2,300 gof 1,6-alkanediol, 2,530 g of fumaric acid, 291 g of trimelliticanhydride, and 4.9 g of hydroquinone. It was reacted first at 160° C.for 5 hours, then heated to 200° C. and reacted for 1 hour, and furtherreacted at 8.3 kPa for 1 hour, and thereby [Crystalline Polyester Resin1] was obtained. [Crystalline Polyester Resin 1] had an endothermic peaktemperature of DSC of 120° C., Mn of 1,500, Mw of 9,000, and an SP valueof 10.8.

—Synthesis of Non-Crystalline Polyester (Low-Molecular-Weight Polyester)Resin—

A 5-L four-necked flask equipped with a nitrogen inlet tube, adehydration tube, a stirrer and a thermocouple was charged with 229parts of 2-mole ethylene-oxide adduct of bisphenol A, 529 parts of3-mole propylene oxide adduct of bisphenol A, 208 parts of terephthalicacid, 46 parts of adipic acid, and 2 parts of dibutyltin oxide. It wasreacted at a normal pressure and at 230° C. for 7 hours and then reactedat a reduced pressure of 10 mmHg to 15 mmHg for 4 hours. Then, 44 partsof trimellitic anhydride was added to the reactor, and it was reacted at180° C. and at a normal pressure for 2 hours. Thereby, [Non-CrystallinePolyester 1] was obtained. [Non-Crystalline Polyester 1] had anumber-average molecular weight (Mn) of 2,200, a weight-averagemolecular weight (Mw) of 5,800, and a glass transition temperature (Tg)of 55° C.

—Synthesis of Polyester Prepolymer—

A reactor equipped with a cooling tube, a stirrer and a nitrogen inlettube was charged with 682 parts of 2-mole ethylene-oxide adduct ofbisphenol A, 81 parts of 2-mole propylene-oxide adduct of bisphenol A,283 parts of terephthalic acid, 22 parts of trimellitic anhydride, and 2parts of dibutyltin oxide. It was reacted at a normal pressure and at230° C. for 8 hours and further reacted at a reduced pressure of 10 mmHgto 15 mmHg for 5 hours, and thereby [Intermediate Polyester 1] wasobtained. [Intermediate Polyester 1] had a number-average molecularweight of 2,100, a weight-average molecular weight of 9,500, Tg of 55°C., an acid value of 0.5, and a hydroxyl value of 51.

Next, a reactor equipped with a cooling tube, a stirrer and a nitrogeninlet tube was charged with 410 parts of [Intermediate Polyester 1], 89parts of isophorone diisocyanate, and 500 parts of ethyl acetate. It wasreacted at 100° C. for 5 hours, and thereby [Prepolymer 1] was obtained.[Prepolymer 1] had free isocyanate % of 1.53%.

—Synthesis of Ketimine—

A reactor equipped with a stirring rod and a thermometer was chargedwith 170 parts of isophoronediamine and 75 parts of methyl ethyl ketone.It was reacted at 50° C. for 5 hours, and [Ketimine Compound 1] wasobtained. [Ketimine Compound 1] had an amine value of 418.

—Preparation of Masterbatch (MB)—

First, 1,200 parts of water, 540 parts of carbon black (PRINTEX35,manufactured by Evonik Degussa) [DBP oil absorption=42 mL/100 mg,pH=9.5], and 1,200 parts of [Non-Crystalline Polyester Resin 1] wereadded and mixed in a HENSCHEL mixer (manufactured by Nippon Coke &Engineering. Co., Ltd.). Then, the mixture was kneaded using a two-rollmill at 150° C. for 30 minutes, rolled and cooled, and then pulverizedwith a pulverizer. Thereby, [Masterbatch 1] was obtained.

—Preparation of Oil Phase—

A container equipped with a stirring rod and a thermometer was chargedwith 378 parts of Non-Crystalline Polyester 1], 110 parts of a carnaubawax, 22 parts of charge controlling agent (CCA, salicylic acid metalcomplex E-84, manufactured by Orient Chemical Industries Co., Ltd.), and947 parts of ethyl acetate. It was heated to 80° C. with stirring,retained at 80° C. for 5 hours and cooled to 30° C. over 1 hour. Next,the container was charged with 500 parts of [Masterbatch 1] and 500parts of ethyl acetate, which was mixed for 1 hour, and thereby[Raw-Material Solution 1] was obtained.

Then, 1,324 parts of [Raw-Material Solution 1] was transferred to acontainer, and using a bead mill (ULTRA VISCO MILL, manufactured byAimex Co., Ltd.) packed by 80% by volume with 0.5-mm zirconia beads, thecarbon black and the wax were dispersed by running 3 passes under theconditions of a liquid feed rate 1 kg/hr and a peripheral speed of adisk of 6 m/second. Next, 1042.3 parts of a 65-% ethyl acetate solutionof [Non-Crystalline Polyester 1] was added, and by running 1 pass withthe bead mill under the above conditions, [Pigment-Wax Dispersion Liquid1] was obtained. A solid content concentration of [Pigment-WaxDispersion Liquid 1] (130° C., 30 minutes) was 50%.

—Preparation of Dispersion Liquid of Crystalline Polyester—

A 2-L container made of metal was charged with 100 g of [CrystallinePolyester Resin 1] and 400 g of ethyl acetate. It was heated anddissolved at 75° C., and then quenched in an ice-water bath at a rate of27° C./min. To this, 500 mL of glass beads (3 mm φ) was added, and itwas subjected to pulverization for 10 hours in a batch-type sand millapparatus. Thereby, [Crystalline Polyester Dispersion Liquid 1] wasobtained.

—Synthesis of Organic-Particle Emulsion—

A reactor equipped with a stirring rod and a thermometer was chargedwith 683 parts of water, 11 parts of sodium salt of sulfuric acid esterof ethylene oxide adduct of methacrylic acid, manufactured by SanyoChemical Industries, Ltd.), 138 parts of styrene, 138 parts ofmethacrylic acid, and 1 part of ammonium persulfate. It was stirred at400 rpm for 15 minutes, and a white emulsion was obtained. It was heatedso that a temperature in the system was increased to 75° C. and reactedfor 5 hours. Further, 30 parts of a 1-% aqueous solution of ammoniumpersulfate was added, and it was aged at 75° C. for 5 hours. Thereby, anaqueous dispersion liquid of a vinyl resin (a copolymer ofstyrene-methacrylic acid-sodium salt of sulfuric acid ester of ethyleneoxide adduct of methacrylic acid) [Fine-Particle Dispersion Liquid 1]was obtained. [Fine-Particle Dispersion Liquid 1] had a volume-averageparticle diameter measured by LA-920 of 0.14 μm. A part of[Fine-Particle Dispersion Liquid 1] was dried, and a resin component wasisolated.

—Preparation of Aqueous Phase—

A milky liquid was obtained by mixing and stirring 990 parts of water,37 parts of a 48.5-% aqueous solution of dodecyl diphenyl ether sodiumdisulfonate (ELEMINOL MON-7, manufactured by Sanyo Chemical Industries,Ltd.), and 90 parts of ethyl acetate were mixed and stirred. This isreferred to as [Aqueous Phase 1].

—Emulsification and Desolvation—

A container was charged with 664 parts of [Pigment-Wax Dispersion Liquid1], 109.4 parts of [Prepolymer 1], 73.9 parts of [Crystalline PolyesterDispersion Liquid 1], and 4.6 parts of [Ketimine Compound 1], which wasmixed by TK HOMOMIXER (manufactured by Primix Corporation) at 5,000 rpmfor 1 minute. Then, 1,200 parts of [Aqueous Phase 1] was added to thecontainer and mixed by TK HOMOMIXER at a rotational speed of 8,000 rpmfor 60 seconds, and [Emulsified Slurry 1] was obtained.

[Emulsified Slurry 1] was placed in a container equipped with a stirrerand a thermometer and was subjected to desolvation at 30° C. for 8 hoursfollowed by aging at 45° C. for 4 hours, and [Dispersion Slurry 1] wasobtained.

—Washing and Drying—

After vacuum filtration of 100 parts of [Dispersion Slurry 1], thefollowing operations were carried out.

(1): To the filter cake, 100 parts of ion-exchanged water was added,which was mixed with TK HOMOMIXER (at a rotational speed of 12,000 rpmfor 10 minutes), followed by filtration.(2): To the filter cake of (1), 100 parts of a 10-% aqueous solution ofsodium hydroxide was added, which was mixed with TK HOMOMIXER (at arotational speed of 12,000 rpm for 30 minutes), followed by vacuumfiltration.(3): To the filter cake of (2), 100 parts of 10-% hydrochloric acid wasadded, which was mixed with TK HOMOMIXER (at a rotational speed of12,000 rpm for 10 minutes), followed by filtration.(4): To the filter cake of (3), 300 parts of ion-exchanged water wasadded, which was mixed with TK HOMOMIXER (at a rotational speed of12,000 rpm for 10 minutes), followed by filtration. This operation wasrepeated twice, and [Filter Cake 1] was obtained.

Thereafter, [Filter Cake 1] was dried in a wind dryer at 45° C. for 48hours and sieved with a mesh having openings of 75 μm, and Toner BaseParticles A were obtained.

(Production of External Additives)

Primary particles of silica having various average particle diameterdescribed in Table 1 below and a treating agent were mixed and baked ina spray dryer to induce coalescence within the primary particles, andthereby External Additives a to q were produced. Also, in order toachieve a sharp particle size distribution as particles of the externaladditives, a classification process was carried out in a classificationapparatus, and coalesced particles having the various average particlediameter described in Table 1 were prepared.

TABLE 1 External Additive Average primary particle diameter of silica(nm) a 43 b 53 c 53 d 21 e 59 f 64 g 147 h 22 i 36 j 47 k 113 l 28 m 53n 54 o 107 p 28 q 59

<External Addition Treatment>

In a HENSCHEL mixer, 2.0 parts of Coalesced Silica a described in Table2, 2.0 parts of silica having an average particle diameter of 20 nm, and0.6 parts of titanium oxide having an average particle diameter of 20 nmwere mixed to 100 parts of Toner Base Particles A. It was sieved with a500 mesh, and thereby Toner 1 was obtained.

Examples 2 to 6

Toner 2 to Toner 6 were obtained in the same manner as Example 1 exceptthat Coalesced Silica a in Example 1 was changed to Coalesced Silica bto Coalesced Silica f, respectively, as the combinations described inTable 2.

Examples 7 to 12 <Production of Toner Base Particles B>

Toner Base Particles B were obtained in the same manner as theproduction process of Toner Base Particles A in Example 1 describedabove except that the mixing time and the aging temperature after theaqueous phase was added in the emulsification and desolvation step werechanged to 90 seconds and 48° C., respectively.

<External Addition Treatment>

Toner 7 to Toner 12 were obtained in the same manner as Example 1 exceptthat Coalesced Silica g to Coalesced Silica 1 were added in place ofCoalesced Silica a according to the combinations of Table 2 to obtainedToner Base Particles B.

Examples 13 to 17 <Production of Toner Base Particles C>

Toner Base Particles C were obtained in the same manner as theproduction process of Toner Base Particles A in Example 1 describedabove except that the mixing time and the aging temperature after theaqueous phase was added in the emulsification and desolvation step werechanged to 40 seconds and 42° C., respectively.

<External Addition Treatment>

Toner 13 to Toner 17 were obtained in the same manner as Example 1except that Coalesced Silica m to Coalesced Silica q were added toobtained Toner Base Particles C in place of Coalesced Silica a accordingto the combinations of Table 2.

Example 18 <Production of Toner Base Particles D> <<Preparation ofSolution or Dispersion Liquid of Toner Materials>> —Synthesis ofNon-Crystalline Polyester (Low-Molecular-Weight Polyester) Resin—

A reactor equipped with a cooling tube, a stirrer and a nitrogen inlettube was charged with 67 parts of 2-mole ethylene-oxide adduct ofbisphenol A, 84 parts of 3-mole propylene-oxide adduct of bisphenol A,274 parts of terephthalic acid, and 2 parts of dibutyltin oxide. It wasreacted at a normal pressure and at 230° C. for 8 hours. Next, thereaction solution was reacted at a reduced pressure of 10 mmHg to 15mmHg for 5 hours, and [Non-Crystalline Polyester 2] was synthesized.

[Non-Crystalline Polyester 2] thus obtained had a number-averagemolecular weight (Mn) of 2,100, a weight-average molecular weight (Mw)of 5,600, and a glass transition temperature (Tg) of 55° C.

—Preparation of Masterbatch (MB)—

First, 1,000 parts of water, 540 parts of carbon black (PRINTEX35,manufactured by Evonik Degussa) [DBP oil absorption=42 mL/100 mg,pH=9.5], and 1,200 parts of the non-modified polyester were mixed usinga HENSCHEL mixer (manufactured by Nippon Coke & Engineering. Co., Ltd.).Then, the mixture was kneaded using a two-roll mill at 150° C. for 30minutes, rolled and cooled, and then pulverized with a pulverizer(manufactured by Hosokawa Micron Co., Ltd.). Thereby, [Masterbatch 2]was prepared.

—Preparation of Wax-Dispersion Liquid—

A reactor equipped with a stirring rod and a thermometer was chargedwith 378 parts of [Non-Crystalline Polyester 2], 110 parts of carnaubawax, 22 parts of salicylic acid metal complex E-84 (manufactured byOrient Chemical Industries Co., Ltd.) and 947 parts of ethyl acetate. Itwas heated to 80° C. with stirring, retained at 80° C. for 5 hours, andthen cooled to 30° C. over 1 hour. Next, the reactor was charged with500 parts of [Masterbatch 2] and 500 parts of ethyl acetate, which wasmixed for 1 hour, and thereby [Raw-Material Solution 2] was obtained.

Then, 1,324 parts of obtained [Raw-Material Solution 2] was transferredto a reactor, and using ULTRA VISCO MILL as a bead mill (manufactured byAimex Co., Ltd.) packed by 80% by volume with 0.5-mm zirconia beads, thecarbon black and the carnauba wax were dispersed by running 3 passesunder the conditions of a liquid feed rate 1 kg/hr and a peripheralspeed of a disk of 6 m/second. Thereby, [Wax Dispersion Liquid 2] wasobtained.

—Preparation of Dispersion Liquid of Toner Materials—

Next, 1324 parts of a 65-% by mass ethyl acetate solution of[Non-Crystalline Polyester 2] was added to [Wax Dispersion Liquid 2]. To200 parts of dispersion liquid obtained by running 1 pass under theabove conditions using ULTRA VISCO MILL, 10 part of layered inorganicmineral montmorillonite modified with a quaternary ammonium salt whichcontains a benzyl group at least at a part thereof (CLAYTON APA,manufactured by Southern Clay Products), which was stirred using a TKHOMODISPER (manufactured by Primix Corporation) for 30 minutes, and[Toner-Material Dispersion Liquid] was obtained.

—Preparation of Aqueous-Medium Phase—

A milky liquid (aqueous phase) was obtained by mixing and stirring 660parts of water, 25 parts of [Fine-Particle Dispersion Liquid 1] above,25 parts of 48.5-% aqueous solution of dodecyl diphenyl ether sodiumdisulfonate (ELEMINOL MON-7, manufactured by Sanyo Chemical Industries,Ltd.), and 60 parts of ethyl acetate. Aggregates of several hundred μmwere observed under an optical microscope. This aqueous-medium phase wasstirred using a TK HOMOMIXER (manufactured by Primix Corporation) at arotational speed of 8,000 rpm, and it was confirmed by an opticalmicroscope that the aggregates were loosened and dispersed into smallaggregates of several μm.

—Preparation of Emulsion or Dispersion Liquid—

A container was charged with 150 parts of the aqueous-medium phase, andit was stirred using a TK HOMOMIXER (manufactured by Primix Corporation)at a rotational speed of 8,000 rpm. To this, 100 parts of[Toner-Material Dispersion Liquid] above was added and mixed for 60seconds, and an emulsion or dispersion liquid (Emulsified Slurry 2) wasprepared.

—Removal of Organic Solvent—

[Emulsified Slurry 2] was placed in a container equipped with a stirrerand a thermometer and subjected to desolvation at 30° C. for 8 hours. Itwas then retained at 45° C. for 4 hours, and [Dispersion Slurry 2] wasobtained.

—Washing and Drying—

After vacuum filtration of 100 parts of [Dispersion Slurry 2], thefollowing operations were carried out.

(1): To the filter cake, 100 parts of ion-exchanged water was added,which was mixed with TK HOMOMIXER (at a rotational speed of 12,000 rpmfor 10 minutes), followed by filtration.(2): To the filter cake of (1), 100 parts of a 10-% aqueous solution ofsodium hydroxide was added, which was mixed with TK HOMOMIXER (at arotational speed of 12,000 rpm for 30 minutes), followed by vacuumfiltration.(3): To the filter cake of (2), 100 parts of 10-% hydrochloric acid wasadded, which was mixed with TK HOMOMIXER (at a rotational speed of12,000 rpm for 10 minutes), followed by filtration.(4): To the filter cake of (3), 300 parts of ion-exchanged water wasadded, which was mixed with TK HOMOMIXER (at a rotational speed of12,000 rpm for 10 minutes), followed by filtration. This operation wasrepeated twice, and [Filter Cake 2] was obtained.

Thereafter, [Filter Cake 2] was dried in a wind dryer at 45° C. for 48hours and sieved with a mesh having openings of 75 μm, and Toner BaseParticles D were obtained.

<External Addition Treatment>

In a HENSCHEL mixer, 2.0 parts of Coalesced Silica a described in Table2, 2.0 parts of silica having an average particle diameter of 20 nm, and0.6 parts of titanium oxide having an average particle diameter of 20 nmwere mixed to 100 parts of Toner Base Particles D. It was sieved with a500 mesh, and thereby Toner 18 was obtained.

Examples 19 to 23

Toner 19 to Toner 23 were obtained in the same manner as Example 18except that Coalesced Silica a in Example 18 was changed to CoalescedSilica b to Coalesced Silica f, respectively, according to thecombinations of Table 2.

Examples 24 to 29 <Production of Toner Base Particles E>

Toner Base Particles E were obtained in the same manner as theproduction process of Toner Base Particles D in Example 18 describedabove except that the mixing time after addition of [Toner-MaterialDispersion Liquid] in the preparation step of the emulsion or dispersionliquid was changed to 90 seconds and that the retaining temperatureafter in the step of removing the organic solvent was changed to 48° C.

<External Addition Treatment>

Toner 24 to Toner 29 were obtained in the same manner as Example 18except that Coalesced Silica g to Coalesced Silica 1 were added toobtained Toner Base Particles E in place of Coalesced Silica a accordingto the combinations of Table 2.

Examples 30 to 34 <Production of Toner Base Particles F>

Toner Base Particles F were obtained in the same manner as theproduction process of Toner Base Particles D in Example 18 describedabove except that the mixing time after addition of [Toner-MaterialDispersion Liquid] in the preparation step of the emulsion or dispersionliquid was changed to 40 seconds and that the retaining temperatureafter in the step of removing the organic solvent was changed to 42° C.

<External Addition Treatment>

Toner 30 to Toner 34 were obtained in the same manner as Example 18except that Coalesced Silica m to Coalesced Silica q were added toobtained Toner Base Particles F in place of Coalesced Silica a accordingto the combinations of Table 2.

Example 35 <Production of Toner Base Particles G> —Preparation of ResinEmulsion—

The following monomers were uniformly mixed, a monomer mixture wasprepared.

Styrene monomer 71 parts n-Butyl acrylate 25 parts Acrylic acid  4 parts

The following aqueous mixture was placed in a reactor and heated to 70°C. with stirring. With stirring at a liquid temperature of 70° C., theabove monomer mixture and 5 parts of a 1-% aqueous solution of potassiumpersulfate respectively were simultaneously dropped over 4 hours, andfurther, it was subjected to polymerization at 70° C. for 2 hours.Thereby, a resin emulsion having a solid content of 50% was obtained.

Water 100 parts Nonionic emulsifier (EMULGEN 950, manufactured by Kao  1part Corporation) Anionic emulsifier (NEOGEN R, manufactured by Dai-ichi 1.5 parts Kogyo Seiyaku Co., Ltd.)

—Preparation of Toner Particles—

The following mixture was retained at 25° C. using a disper withstirring for 2 hours.

Pigment 20 parts (Carbon black (PRINTEX35, manufactured by EvonikDegussa, DBP oil absorption = 42 mL/100 g, pH = 9.5) Charge controllingagent (E-84, manufactured by 1 part Orient Chemical Industries Co.,Ltd.) Anionic emulsifier (NEOGEN R, manufactured by 0.5 parts Dai-ichiKogyo Seiyaku Co., Ltd.) Water 310 parts

Next, 188 parts of the above emulsion was added to this dispersionliquid and stirred for about 2 hours. Then, it was heated to 60° C., anda pH thereof was adjusted to 7.0 with ammonia. Further, this dispersionliquid was heated to 90° C. and retained at this temperature for 2hours, and [Dispersion Slurry 3] was obtained.

After vacuum filtration of 100 parts of [Dispersion Slurry 3], thefollowing operations were carried out.

(1): To the filter cake, 100 parts of ion-exchanged water was added,which was mixed with TK HOMOMIXER (at a rotational speed of 12,000 rpmfor 10 minutes), followed by filtration.(2): To the filter cake of (1), 10-% hydrochloric acid was added toadjust a pH thereof to 2.8, which was mixed with TK HOMOMIXER (at arotational speed of 12,000 rpm for 10 minutes), followed by vacuumfiltration.(3): To the filter cake of (2), 300 parts of ion-exchanged water wasadded, which was mixed with TK HOMOMIXER (at a rotational speed of12,000 rpm for 10 minutes), followed by filtration. This operation wasrepeated twice, and [Filter Cake 3] was obtained.

Thereafter, [Filter Cake 3] was dried in a wind dryer at 45° C. for 48hours and sieved with a mesh having openings of 75 μm, and Toner BaseParticles G were obtained.

<External Addition Treatment>

In a HENSCHEL mixer, 2.0 parts of Coalesced Silica a described in Table2, 2.0 parts of silica having an average particle diameter of 20 nm, and0.6 parts of titanium oxide having an average particle diameter of 20 nmwere mixed to 100 parts of Toner Base Particles G. It was sieved with a500 mesh, and thereby Toner 35 was obtained.

Examples 36 to 40

Toner 36 to Toner 40 were obtained in the same manner as Example 35except that Coalesced Silica a in Example 35 was changed to CoalescedSilica b to Coalesced Silica f, respectively, according to thecombinations of Table 2.

Examples 41 to 46 <Production of Toner Base Particles H>

Toner Base Particles H were obtained in the same manner as theproduction process of Toner Base Particles G in Example 35 describedabove except that the stirring temperature after addition of theemulsion to the dispersion liquid to 55° C. and that the retention timeafter heating during preparation of the dispersion slurry was changed to6 hours.

<External Addition Treatment>

Toner 41 to Toner 46 were obtained in the same manner as Example 35except that Coalesced Silica g to Coalesced Silica I were added toobtained Toner Base Particles H in place of Coalesced Silica a accordingto the combinations of Table 2.

Examples 47 to 51 <Production of Toner Base Particles I>

Toner Base Particles I were obtained in the same manner as theproduction process of Toner Base Particles G in Example 35 describedabove except that the stirring temperature after the addition of theemulsion to the dispersion liquid was changed to 65° C. and that theheating temperature during preparation of the dispersion slurry waschanged to 80° C.

<External Addition Treatment>

Toner 47 to Toner 51 were obtained in the same manner as Example 35except that Coalesced Silica in to Coalesced Silica q were added toobtained Toner Base Particles I in place of Coalesced Silica a accordingto the combinations of Table 2.

Comparative Example 1 <Production of Toner Base Particles J>

Toner Base Particles J were prepared by changing the aging temperaturein the emulsification and desolvation step in the production process of[Toner 1] in Example 1 described above was changed to 50° C.

<External Addition Treatment>

Toner 52 was obtained in the same manner as Example 1 except thatCoalesced Silica a externally added to the toner base particles waschanged to non-coalesced Spherical Silica r (average particle diameterof 120 nm) to obtained Toner Base Particles J according to Table 2.

Comparative Example 2

Toner 53 was obtained in the same manner as Comparative Example 1 exceptthat Spherical Silica r externally added to Toner Base Particles J waschanged to Coalesced Silica a as indicated in Table 2.

Comparative Example 3

Toner 54 was obtained in the same manner as Comparative Example 1 exceptthat Spherical Silica r externally added to Toner Base Particles J waschanged to Coalesced Silica c as indicated in Table 2.

Comparative Example 4

Toner 55 was obtained in the same manner as Comparative Example 1 exceptthat Spherical Silica r externally added to Toner Base Particles J waschanged to Coalesced Silica e as indicated in Table 2.

Comparative Example 5

Toner 56 was obtained in the same manner as Example 1 except thatCoalesced Silica a externally added to Toner Base Particles A waschanged to Spherical Silica r as indicated in Table 2.

Comparative Example 6 <Production of Toner Base Particles L>

Toner Base Particles L was prepared by changing the aging temperature inthe emulsification and desolvation step in the production process of[Toner 1] in Example 1 described above was changed to 40° C.

<External Addition Treatment>

Toner 57 was obtained in the same mariner as Example 1 except that TonerBase Particles A were changed to Toner Base Particles L and thatCoalesced Silica a externally added to the toner base particles waschanged to Spherical Silica r.

Comparative Example 7

Toner 58 was obtained in the same manner as Comparative Example 6 exceptthat Spherical Silica r externally added to Toner Base Particles L waschanged to Coalesced Silica a as indicated in Table 2.

Comparative Example 8

Toner 59 was obtained in the same manner as Comparative Example 6 exceptthat Spherical Silica r externally added to Toner Base Particles L waschanged to Coalesced Silica c as indicated in Table 2.

Comparative Example 9

Toner 60 was obtained in the same manner as Comparative Example 6 exceptthat Spherical Silica r externally added to Toner Base Particles L waschanged to Coalesced Silica e as indicated in Table 2.

Comparative Example 10

Toner 61 was obtained in the same manner as Example 30 except thatCoalesced Silica m externally added to Toner Base Particles F waschanged to Spherical Silica r as indicated in Table 2.

[Evaluation Items] (Transfer Stability)

A chart with an image area ratio of 20% was transferred from aphotoconductor to paper. Then, a transfer residual toner on aphotoconductor right before cleaning was transferred to blank paper witha scotch tape (manufactured by Sumitomo 3M Ltd.), which was measuredwith a Macbeth reflection densitometer RD514 type and evaluated based onthe following criteria.

—Evaluation Criteria—

A: A difference from the blank was less than 0.005.

B: A difference from the blank was 0.005 to 0.010.

C: A difference from the blank was 0.011 to 0.02.

D: A difference from the blank exceeded 0.02.

A, B and C were determined as acceptable, and D was determined asunacceptable.

(Filming Evaluation Method)

1. All the toners and apparatuses used for the evaluation were allowedto stand in an environmental chamber of 25° C. and RH 50% for 1 day.2. A toner in a PCU of a copier was completely removed, leaving only acarrier in a developing apparatus.3. In the developing apparatus including only the carrier, 28 g of ablack toner as a sample was placed, and 400 g of a developer having atoner concentration of 7% was prepared.4. The developing apparatus was mounted on the copier main body, andonly the developing apparatus was run idle for 5 minutes with a linearspeed of a developing sleeve (a sleeve which forms a surface of adeveloping roller) of 300 mm/s.5. By rotating both the developing sleeve and a photoconductor at anaimed linear velocity with trailing, a charge potential and a developingbias were adjusted such that the toner on the photoconductor was0.4±0.05 mg/cm².6. In the above developing conditions, a transfer current was adjustedso that a transfer rate was 96±2%.7. Ten thousand (10,000) sheets of a fully solid image were continuouslyprinted out.8. An image quality of the printed image was subjected to sensoryevaluation, and a number of white spots due to filming was counted.

Evaluation criteria of filming property were as follows.

—Evaluation Criteria—

A: Superior with less white-spot portions.

B: White-spot portions were occasionally observed.

C: White-spot portions were noticeable.

D: There were many white-spot portions.

A, B and C were determined as acceptable, and D was determined asunacceptable.

(Low-Temperature Fixing Property)

Using an apparatus that a fixing unit of a copier MF2200 (manufacturedby Ricoh Company, Ltd.) using a TEFLON (registered trademark) roller asa fixing roller was remodeled, a copying test was carried out on TYPE6200 paper (manufactured by Ricoh Company, Ltd.).

Specifically, a cold-offset temperature (minimum fixing temperature) wasobtained with a fixing temperature varied.

As evaluation conditions of the minimum fixing temperature, a linearvelocity of paper feed was 120 mm/sec to 150 mm/sec, a surface pressurewas 1.2 kgf/cm², and a nip width was 3 mm.

Here, a conventional low-temperature fixing toner has a minimum fixingtemperature of around 140° C.

—Evaluation Criteria—

A: The minimum fixing temperature was less than 120° C.

B: The minimum fixing temperature was 120° C. or greater and less than130° C.

C: The minimum fixing temperature was 130° C. or greater and less than140° C.

D: The minimum fixing temperature was 140° C. or greater.

A, B and C were determined as acceptable, and D was determined asunacceptable.

(Storage Stability)

A toner was stored at 40° C., RH 70% for 14 days, and it was sieved witha 200 mesh for 1 minute, and a remaining ratio on the mesh was measured.

At this time, a toner having more favorable storage stability in ahigh-humidity environment has a smaller remaining ratio.

—Evaluation Criteria—

A: The remaining ratio was less than 0.1%.

B: The remaining ratio was 0.1% or greater and less than 0.5%.

C: The remaining ratio was 0.5% or greater and less than 1%.

D: The remaining ratio was 1% or greater.

A, B and C were determined as acceptable, and D was determined asunacceptable.

The evaluation results of produced Toner 1 to Toner 61 are shown inTable 3.

TABLE 2 Toner base particles Coalesced silica Base Base Average AverageToner vol.-avg. BET secondary value of Number of base particle surfaceparticle degree of particles Toner particles diameter area diametercoalescence with G <1.3 Db₁₀ Db₅₀ name name (um) (m²/g) Silica Dba (nm)G = Db/Da (number %) (nm) (nm) Db₅₀/Db₁₀ Ex. 1 Toner 1 A 5.0 3.5 a 1002.2 6 84 96 1.14 Ex. 2 Toner 2 A 5.0 3.5 b 85 1.7 12 69 82 1.19 Ex. 3Toner 3 A 5.0 3.5 c 74 1.4 8 60 70 1.17 Ex. 4 Toner 4 A 5.0 3.5 d 76 3.916 67 80 1.19 Ex. 5 Toner 5 A 5.0 3.5 e 213 3.7 7 182 206 1.13 Ex. 6Toner 6 A 5.0 3.5 f 90 1.3 12 71 85 1.2 Ex. 7 Toner 7 B 4.0 2.5 g 1761.4 7 152 174 1.14 Ex. 8 Toner 8 B 4.0 2.5 h 92 4.2 11 76 90 1.18 Ex. 9Toner 9 B 4.0 2.5 i 172 4.6 9 148 168 1.14 Ex. 10 Toner 10 B 4.0 2.5 j206 4.8 12 168 200 1.19 Ex. 11 Toner 11 B 4.0 2.5 k 192 1.7 18 154 1881.22 Ex. 12 Toner 12 B 4.0 2.5 l 83 3.2 14 65 80 1.23 Ex. 13 Toner 13 C6.0 5.0 m 185 3.7 20 148 183 1.24 Ex. 14 Toner 14 C 6.0 5.0 n 81 1.6 1761 77 1.26 Ex. 15 Toner 15 C 6.0 5.0 o 182 1.5 14 144 180 1.25 Ex. 16Toner 16 C 6.0 5.0 p 90 3.4 17 70 86 1.23 Ex. 17 Toner 17 C 6.0 5.0 q178 3.2 16 144 174 1.21 Ex. 18 Toner 18 D 5.2 3.3 a 100 2.2 6 84 96 1.14Ex. 19 Toner 19 D 5.2 3.3 b 85 1.7 12 69 82 1.19 Ex. 20 Toner 20 D 5.23.3 c 74 1.4 8 60 70 1.17 Ex. 21 Toner 21 D 5.2 3.3 d 76 3.9 16 67 801.19 Ex. 22 Toner 22 D 5.2 3.3 e 213 3.7 7 182 206 1.13 Ex. 23 Toner 23D 5.2 3.3 f 90 1.3 12 71 85 1.2 Ex. 24 Toner 24 E 4.4 2.5 g 176 1.4 7152 174 1.14 Ex. 25 Toner 25 E 4.4 2.5 h 92 4.2 11 76 90 1.18 Ex. 26Toner 26 E 4.4 2.5 i 172 4.6 9 148 168 1.14 Ex. 27 Toner 27 E 4.4 2.5 j206 4.8 12 168 200 1.19 Ex. 28 Toner 28 E 4.4 2.5 k 192 1.7 18 154 1881.22 Ex. 29 Toner 29 E 4.4 2.5 l 83 3.2 14 65 80 1.23 Ex. 30 Toner 30 F6.0 4.8 m 185 3.7 20 148 183 1.24 Ex. 31 Toner 31 F 6.0 4.8 n 81 1.6 1761 77 1.26 Ex. 32 Toner 32 F 6.0 4.8 o 182 1.5 14 144 180 1.25 Ex. 33Toner 33 F 6.0 4.8 p 90 3.4 17 70 86 1.23 Ex. 34 Toner 34 F 6.0 4.8 q178 3.2 16 144 174 1.21 Ex. 35 Toner 35 G 5.0 3.5 a 100 2.2 6 84 96 1.14Ex. 36 Toner 36 G 5.0 3.5 b 85 1.7 12 69 82 1.19 Ex. 37 Toner 37 G 5.03.5 c 74 1.4 8 60 70 1.17 Ex. 38 Toner 38 G 5.0 3.5 d 76 3.9 16 67 801.19 Ex. 39 Toner 39 G 5.0 3.5 e 213 3.7 7 182 206 1.13 Ex. 40 Toner 40G 5.0 3.5 f 90 1.3 12 71 85 1.2 Ex. 41 Toner 41 H 4.3 2.5 g 176 1.4 7152 174 1.14 Ex. 42 Toner 42 H 4.3 2.5 h 92 4.2 11 76 90 1.18 Ex. 43Toner 43 H 4.3 2.5 i 172 4.6 9 148 168 1.14 Ex. 44 Toner 44 H 4.3 2.5 j206 4.8 12 168 200 1.19 Ex. 45 Toner 45 H 4.3 2.5 k 192 1.7 18 154 1881.22 Ex. 46 Toner 46 H 4.3 2.5 l 83 3.2 14 65 80 1.23 Ex. 47 Toner 47 I5.7 4.2 m 185 3.7 20 148 183 1.24 Ex. 48 Toner 48 I 5.7 4.2 n 81 1.6 1761 77 1.26 Ex. 49 Toner 49 I 5.7 4.2 o 182 1.5 14 144 180 1.25 Ex. 50Toner 50 I 5.7 4.2 p 90 3.4 17 70 86 1.23 Ex. 51 Toner 51 I 5.7 4.2 q178 3.2 16 144 174 1.21 Comp. Ex. 1 Toner 52 J 5.7 4.2 r Comp. Ex. 2Toner 53 J 4.2 2.3 a 100 2.2 6 84 96 1.14 Comp. Ex. 3 Toner 54 J 4.2 2.3c 74 1.4 8 60 70 1.17 Comp. Ex. 4 Toner 55 J 4.2 2.3 e 213 3.7 7 182 2061.13 Comp. Ex. 5 Toner 56 A 5.0 3.5 r Comp. Ex. 6 Toner 57 L 6.4 5.2 rComp. Ex. 7 Toner 58 L 6.4 5.2 a 100 2.2 6 84 96 1.14 Comp. Ex. 8 Toner59 L 6.4 5.2 c 74 1.4 8 60 70 1.17 Comp. Ex. 9 Toner 60 L 6.4 5.2 e 2133.7 7 182 206 1.13 Comp. Ex. 10 Toner 61 F 6.0 4.8 r

TABLE 3 Transfer Filming Low-temperature Storage Overall Toner namestability property fixing property stability judgment Ex. 1 Toner 1 A AA A A Ex. 2 Toner 2 A A A A A Ex. 3 Toner 3 A A A A A Ex. 4 Toner 4 A AA A A Ex. 5 Toner 5 A A A A A Ex. 6 Toner 6 B A A C B Ex. 7 Toner 7 A CB A B Ex. 8 Toner 8 A B A B A Ex. 9 Toner 9 B B A B B Ex. 10 Toner 10 CA A B B Ex. 11 Toner 11 B C B A B Ex. 12 Toner 12 B A A B A Ex. 13 Toner13 B B A C B Ex. 14 Toner 14 B A A C B Ex. 15 Toner 15 B C B B B Ex. 16Toner 16 C A A C B Ex. 17 Toner 17 C C B B B Ex. 18 Toner 18 A A B B AEx. 19 Toner 19 A A B B A Ex. 20 Toner 20 A A B B A Ex. 21 Toner 21 A AC A A Ex. 22 Toner 22 A A B B A Ex. 23 Toner 23 B A A C B Ex. 24 Toner24 A C C A B Ex. 25 Toner 25 A B A C B Ex. 26 Toner 26 B B B B B Ex. 27Toner 27 C A B B B Ex. 28 Toner 28 B C C A B Ex. 29 Toner 29 B A A C BEx. 30 Toner 30 B B B B B Ex. 31 Toner 31 B A A C B Ex. 32 Toner 32 B CC A B Ex. 33 Toner 33 C A A C B Ex. 34 Toner 34 C C C A B Ex. 35 Toner35 A A B B A Ex. 36 Toner 36 A A C B B Ex. 37 Toner 37 A A B B A Ex. 38Toner 38 A A C B B Ex. 39 Toner 39 A A C B B Ex. 40 Toner 40 B A A C BEx. 41 Toner 41 A C C B B Ex. 42 Toner 42 A B A C B Ex. 43 Toner 43 B BB B B Ex. 44 Toner 44 C A A C B Ex. 45 Toner 45 B C C B B Ex. 46 Toner46 B A A C B Ex. 47 Toner 47 B B C B B Ex. 48 Toner 48 B A A C B Ex. 49Toner 49 B C C B B Ex. 50 Toner 50 C A A C B Ex. 51 Toner 51 C C C B BComp. Ex. 1 Toner 52 D D A C D Comp. Ex. 2 Toner 53 C B D A D Comp. Ex.3 Toner 54 D C D B D Comp. Ex. 4 Toner 55 C D B B D Comp. Ex. 5 Toner 56D B A C D Comp. Ex. 6 Toner 57 D D C D D Comp. Ex. 7 Toner 58 D B B C DComp. Ex. 8 Toner 59 B D D B D Comp. Ex. 9 Toner 60 D B D B D Comp. Ex.10 Toner 61 D D B D D

Aspects of the present invention are as follows.

<1> A toner for developing an electrostatic image, including:

toner base particles each including a binder resin and a releasingagent; and

inorganic fine particles as an external additive on a surface of thetoner base particle,

wherein the toner base particles have a BET specific surface area of 2.5m²/g to 5.0 m²/g, and

wherein the inorganic fine particles include inorganic fine particles(A) which are each a secondary particle where a plurality of primaryparticles are coalesced together.

<2> The toner for developing an electrostatic image according to <1>,

wherein the BET specific surface area of the toner base particles is 3.5m²/g to 5.0 m²/g.

<3> The toner for developing an electrostatic image according to <1> or<2>,

wherein the inorganic fine particles (A) have Db₅₀/Db₁₀ of 1.20 or less,where Db₅₀ is a particle diameter at which a cumulative percentage of asecondary particle diameter Db of the inorganic fine particles (A)measured from a side of smaller particles is 50% by number, and Db₁₀ isa particle diameter at which the cumulative percentage measured from theside of smaller particles is 10% by number.

<4> The toner for developing an electrostatic image according to any oneof <1> to <3>,

wherein the inorganic fine particles (A) have an average of degrees ofcoalescence G of 1.5 to 4.0, where each of the degrees of coalescence isdefined as a ratio (Db/Da) with Db being the secondary particle diameterof the inorganic fine particles (A) and Da being an average primaryparticle diameter of the plurality of primary particles forming theinorganic fine particles (A).

<5> The toner for developing an electrostatic image according to any oneof <1> to <4>,

wherein a content of the inorganic fine particles (A) having the degreeof coalescence G of less than 1.3 in the inorganic fine particles (A) is10% by number or less.

<6> The toner for developing an electrostatic image according to any oneof <1> to <5>,

wherein the inorganic fine particles (A) have an average secondaryparticle diameter Dba of 80 nm to 200 nm.

<7> The toner for developing an electrostatic image according to any oneof <1> to <6>,

wherein the toner is granulated in an aqueous medium.

<8> The toner for developing an electrostatic image according to any oneof <1> to <7>,

wherein the toner is obtained by: dispersing an oil phase in an aqueousmedium to prepare an emulsified dispersion, the oil phase being obtainedby dissolving or dispersing, in an organic solvent, toner materialsincluding a polyester resin, a colorant and a releasing agent; andremoving the organic solvent from the emulsified dispersion.

<9> A two-component developer, including:

the toner for developing an electrostatic image according to any one of<1> to <8>; and

a carrier.

<10> An image forming apparatus: including:

an electrostatic latent image bearing member;

an electrostatic latent image forming unit which forms an electrostaticlatent image on the electrostatic latent image bearing member;

a developing unit which includes the toner for developing anelectrostatic image according to any one of <1> to <8> and which forms avisible image by developing the electrostatic latent image with thetoner;

a transfer unit which transfers the visible image on the electrostaticlatent image bearing member to a recording medium;

a fixing unit which fixes the visible image transferred on the recordingmedium; and

a cleaning unit which removes the toner remaining on the image bearingmember.

This application claims priority to Japanese application No.2012-061685, filed on Mar. 19, 2012 and incorporated herein byreference.

What is claimed is:
 1. A toner for developing an electrostatic image,comprising: toner base particles each comprising a binder resin and areleasing agent; and inorganic fine particles, wherein the tonercomprises the inorganic fine particles as an external additive on asurface of the toner base particle, wherein the toner base particleshave a BET specific surface area of 2.5 m²/g to 5.0 m²/g, and whereinthe inorganic fine particles comprise inorganic fine particles (A) whichare each a secondary particle where a plurality of primary particles arecoalesced together.
 2. The toner for developing an electrostatic imageaccording to claim 1, wherein the BET specific surface area of the tonerbase particles is 3.5 m²/g to 5.0 m²/g.
 3. The toner for developing anelectrostatic image according to claim 1, wherein the inorganic fineparticles (A) have Db₅₀/Db₁₀ of 1.20 or less, where Db₅₀ is a particlediameter at which a cumulative percentage of a secondary particlediameter Db of the inorganic fine particles (A) measured from a side ofsmaller particles is 50% by number, and Db₁₀ is a particle diameter atwhich the cumulative percentage measured from the side of smallerparticles is 10% by number.
 4. The toner for developing an electrostaticimage according to claim 1, wherein the inorganic fine particles (A)have an average of degrees of coalescence G of 1.5 to 4.0, where each ofthe degrees of coalescence is defined as a ratio (Db/Da) with Db beingthe secondary particle diameter of the inorganic fine particles (A) andDa being an average primary particle diameter of the plurality ofprimary particles forming the inorganic fine particles (A).
 5. The tonerfor developing an electrostatic image according to claim 1, wherein acontent of the inorganic fine particles (A) having the degree ofcoalescence G of less than 1.3 in the inorganic fine particles (A) is10% by number or less.
 6. The toner for developing an electrostaticimage according to claim 1, wherein the inorganic fine particles (A)have an average secondary particle diameter Dba of 80 nm to 200 nm. 7.The toner for developing an electrostatic image according to claim 1,wherein the toner is granulated in an aqueous medium.
 8. The toner fordeveloping an electrostatic image according to claim 1, wherein thetoner is obtained by: dispersing an oil phase in an aqueous medium toprepare an emulsified dispersion, the oil phase being obtained bydissolving or dispersing, in an organic solvent, toner materialscomprising a polyester resin, a colorant and a releasing agent; andremoving the organic solvent from the emulsified dispersion.
 9. Atwo-component developer, comprising: a toner for developing anelectrostatic image, and a carrier, wherein the toner comprises: tonerbase particles each comprising a binder resin and a releasing agent, andinorganic fine particles, wherein the toner comprises the inorganic fineparticles as an external additive on a surface of the toner baseparticle, wherein the toner base particles have a BET specific surfacearea of 2.5 m²/g to 5.0 m²/g, and wherein the inorganic fine particlescomprise inorganic fine particles (A) which are each a secondaryparticle where a plurality of primary particles are coalesced together.10. An image forming apparatus, comprising: an electrostatic latentimage bearing member; an electrostatic latent image forming unit whichforms an electrostatic latent image on the electrostatic latent imagebearing member; a developing unit which comprises a toner for developingan electrostatic image and which forms a visible image by developing theelectrostatic latent image with the toner; a transfer unit whichtransfers the visible image on the electrostatic latent image bearingmember to a recording medium; a fixing unit which fixes the visibleimage transferred on the recording medium; and a cleaning unit whichremoves the toner remaining on the image bearing member, wherein thetoner comprises: toner base particles each comprising a binder resin anda releasing agent, and inorganic fine particles, wherein the tonercomprises the inorganic fine particles as an external additive on asurface of the toner base particle, wherein the toner base particleshave a BET specific surface area of 2.5 m²/g to 5.0 m²/g, and whereinthe inorganic fine particles comprise inorganic fine particles (A) whichare each a secondary particle where a plurality of primary particles arecoalesced together.